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Comet Atlas could be the brightest comet in decades – The Next Web

Comet Atlas is racing toward the inner solar system, and it could become the brightest comet seen in the night sky in over two decades. The comet, discovered by an observatory designed to protect Earth from asteroids, may even be visible during the day just two months from now.

Also known as C/2019 Y4, this comet was discovered by astronomers at the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Hawaii in December 2019. At the time, the comet was exceedingly dim but the comet became 4,000 times brighter in just a month. This increase is far greater than astronomers predicted, and could potentially signal the comet may soon be exceptionally bright.

Comet ATLAS continues to brighten much faster than expected. Some predictions for its peak brightness now border on the absurd, statedKarl Battamsof the Naval Research Lab.

Comets are, essentially, dirty snowballs. As the comet approaches the Sun, the heat will drive off some of the ice which makes up the nucleus (main body) of the object. If the comet holds it shape as it continues to heat, then Comet Atlas could grow as bright as the planet Venus (the brightest object in the night sky other than the Moon).

The comet, currently near the orbit ofMars, is closely following the path taken by one of the great comets in history the Great Comet of 1844.

At its current rate of brightening, Comet Atlas could be visible to the naked eye, under dark skies, during the first weeks of April. For skywatchers in the northern hemisphere, this would be a sight unseen since the dual shows of Comets Hyakutake in 1996 and Hale-Bopp the following year. When Hyakutake was at its peak, the tail of the comet stretched halfway across the sky.

In May, the comet could shine with a green hue, providing a unique view for viewers in the northern hemisphere.The brightest predictions for the comet suggest it could become bright enough to be seen during the day.

The peak brightness of Comet Atlas would depend, largely, on how much material is encased within its nucleus. If the comet is sizable, and it does not fall apart as it is heated by theSun, it could put on an amazing show in May.

The ATLAS observatory which first spotted the comet consists of a pair of 0.5-meter (19) telescopes, placed 160 kilometers (100 miles) apart. The system, operating since 2017, is designed to detect near-Earth objects asteroids and other bodieswhich could potentially impact Earth. In addition to finding roughly 100 space rocks measuring 30 meters (100 feet) in diameter or larger every year, the observatory also occasionally discovers comets.

When it was first spotted on December 28, the comet was 439 million kilometers (273 million miles) from theSun. At its closest approach, Comet Atlas will come within 37.8 million kilometers (23.5 million miles) of our parent star. The comet is brightening at nearly an unprecedented rate and by March 17, the comet was already 600 times brighter than predicted.

Thecometis currently in the constellation of Ursa Major (which includes the Big Dipper) and it will remain visible all night (as seen from the northern hemisphere) all night during it pass through the inner solar system.

Severalcometsastronomers thought were destined for greatness failed to achieve their potential. In 2013, Comet PANSTARRS became as bright as Sirius (the brightest star in the sky), but it was positioned low on the horizon as seen from the northern hemisphere, making it difficult to see. The last two brightcomets McNaught in 2007 and Lovejoy in 2011 were only visible from the southern hemisphere.

The path traveled by Comet Atlas the same as that take by the Great Comet of 1844 suggests that each of these bodies (and potentially others) may have broken off of an ancient mega-comet long ago. The Great Comet of 1844 was first seen by observers at the Cape of Good Hope on December 18 of that year, and was visible without the aid of a telescope through January 1845.

During the latter part of December and the first week in January, it was a brilliant objects in the southern hemisphere, equaling, it is said, in brightness the celebrated comet of Halley in its last appearance,The Astronomical Journalreported in 1850.

Out to sea, the calm lagoon waters were darkening, while the comets overhead glowed brighter, omens in the gloaming. Julian May, Perseus Spur

Comets are one of the most beautiful sights to see in the night sky, and they make perfect targets for families to view together, creating a lifetime of memories.

Of course, the behavior of comets is notoriously difficult to predict, and some comets once thought to be destined for greatness fizzled.

In 1974, many astronomers believed Comet Kohoutek would light up the night sky, but it failed to deliver. Similar expectations were dashed by Comets Austin in 1990 and ISON in 2013.

If this comet fails to live up to its potential, it will be a long time before we see it again once it heads out to the outersolar system, it will not return for another 6,000 years.

This article was originally published onThe Cosmic Companionby James Maynard, an astronomy journalist, fan of coffee, sci-fi, movies, and creativity. Maynard has been writing about space since he was 10, but hes still not Carl Sagan. The Cosmic Companionsmailing list/podcast. You can read this original piecehere.

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Comet Atlas could be the brightest comet in decades - The Next Web

Comets have enjoyed extended run of success on court – The Abington Journal

The pinnacle is easy to define.

On the night of March 27, 2018 at the Giant Center in Hershey, the Abington Heights boys basketball team reached the top, winning a Pennsylvania Interscholastic Athletic Association Class 5A state title with a 67-55 victory over Mars.

The state title was part of a lengthy run of success that, by some measurements, came to an end in the recently completed season.

Defining the most impressive long-term accomplishment is not as easy as recognizing the most significant single moment. The run has included coach Ken Bianchi becoming the all-time leader among District 2 coaches and picking up his 800th career win.

Even saying the run is over is not definitive because, after all, the Comets did win a Lackawanna League Division 1 title again this season, their third straight, starting with the state championship team.

Longer streaks, however, were halted in a pair of District 2 tournament losses.

Abington Heights had won eight straight district championships before falling, 49-39, in this seasons semifinals against Dallas, a team that is still one of eight quarterfinalists left in the suspended state tournament.

Dallas also ended a 27-game winning streak by the Comets in District 2 or District 2-4 Subregional playoff games.

The Comets still had a chance to find a way into their 14th straight state tournament.

All semifinalists in Class 5A have two shots at the state tournament because the districts top three teams advance. Corey Perkins, a starter on the state championship team two years earlier, made sure the second chance was available with his buzzer-beater to complete a 48-46 rally over North Pocono in the quarterfinals when the streaks first appeared in jeopardy of ending.

Abington Heights, however, was unable to repeat that dramatic finish in the districts third-place game, losing to Pittston Area, 37-35, to stop the streak of state tournament trips at 13.

The loss also ended any chance of the Comets reaching the state Final Four for the fourth straight season and of posting 20-plus wins for a ninth straight season.

Still, there are many impressive cumulative numbers that have been run up by the Abington Heights boys basketball team in the 14-year stretch that started with qualifying for the state tournament in 2007.

Here are some of them:

Division titles. The Comets have nine in 14 years, beginning with four straight titles in what was then an eight-team Division 1 of the Lackawanna League from the 2006-07 season through 2009-10. They won back-to-back titles again in 2012-13 and 2013-14, then the current streak of three straight.

Perfect seasons. Abington Heights went 14-0 in the Lackawanna League in 2008-09 and 13-0 in 2012-13, 2013-14 and 2018-19.

Winning records. The Comets have finished in the top half of the league all 14 seasons with the nine titles, three second-place finishes in the current five-team division plus a tie for third and a fourth-place finish in the old eight-team Division 1.

Winning percentage. The Comets have gone a combined 164-24 in the league for an .872 winning percentage in that time.

Better in playoffs. Prior to losing two straight to Dallas and Pittston Area, the Comets had been 39-3 in district playoff games over the past 14 seasons. Even with the losses, they have a higher winning percentage in district playoff games (.886) than league play with their 39-5 record.

State success. Beginning in 2009, Abington Heights won at least one state playoff game in nine of 11 seasons and at least two in seven of those seasons. After going 2-11 in state playoff games since 2009, the Comets are 19-9 since.

Overall record. Despite consistently seeking out a non-league schedule that includes some of the states top programs, the Comets have won 22 or more games in 12 of the last 14 seasons for an overall record of 329-67 and overall winning percentage of .831.

The first state final appearance came about only after the Comets escaped a controversial technical foul in the final second for fans throwing Hersheys Kisses on the floor in celebration. The resulting free throws put the game in overtime where Abington Heights prevailed over Bonner-Prendergast, 56-51, to reach the 2018 final.

Once there, first-team, all-stater George Tinsley scored 29 points, including 19 in the second half.

At the beginning of the second half, I started taking it to the rack a little bit more, Tinsley, the America East Conferences Rookie of the Year at Binghamton University this season, said after reaching 1,000 points for his career with his final points of the night.

The Comets overcame some serious obstacles.

The teams other first-team, all-stater, Jackson Danzig, now a two-year starter at the University of Scranton, was limited to 11 points and four assists because of foul trouble. He left the game for good with 5:23 to go.

Notre Dame-bound Robby Carmody scored 27 of his 34 points in the second half for Mars, but there was no stopping the Comets.

Tinsley took over in a game that the Comets had trailed in at halftime.

Jack Nealon went 5-for-6 from the line in the final 1:26 to finish with 13 points and 4 assists.

Perkins went 3-for-6 on 3-pointers while providing 11 points and six rebounds.

They left me open, so I made them pay for it, said Perkins, who joined Mike Malone as sophomore starters on the state championship team that went the bulk of the season without returning all-star Trey Koehler, a current Ursinus College player, because of a foot injury.

The championship was the highlight of a successful run by the Abington Heights boys basketball program while also representing an end to struggles by District 2 teams.

The state title was the first by a District 2 basketball team since Bishop OReilly had won back-to-back in 2004 and 2005 and the first by a Lackawanna League team since Bishop Hannan in 2002. All three of those titles came in Class A boys, as opposed to the Abington Heights championship in the second-largest of six enrollment classifications.

Abington Heights players and coaches celebrate as the final seconds tick off the clock during the 2018 PIAA Class 5A boys basketball game at the GIANT Center in Hershey.

Abington Heights co-captains Jackson Danzig, left, and George Tinsley hold the championship trophy and a chocolate bar after the Comets won the 2018 PIAA Class 5A boys basketball title in Hershey.

Abington Heights guard Jackson Danzig drives to the basket during the 2018 PIAA Class 5A boys basketball title game in Hershey.

The Abington Heights players and coaching staff pose for a photo after the Comets won the first boys basketball championship in school history in 2018.

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Comets have enjoyed extended run of success on court - The Abington Journal

Comet coming towards the Earth caught on camera, and it’s called C19 – MyLondon

A photographer has caught on camera a massive comet coming towards Earth - and it's called C19.

The comet, named C/2019 Y4 (ATLAS), is pictured glimmering in space by Jamie Cooper in Lincolnshire.

The celestial body will be visible to the naked eye within weeks as it zooms brightly in the atmosphere.

In one picture a fuzzy outer-layer of light can also be seen around the comet, known as the coma.

The comet was first spotted on the 28th December 2019, days before the first reported cases of coronavirus in Wuhan, China.

Astrophotographer Jamie loves to take pictures of the natural world and can add C/2019 Y4 (ATLAS) to his collection.

He said: ''Comets have been feared throughout human history as harbingers of doom.

"Well there is one heading our way Comet C/2019 Y4 (ATLAS) - which is expected to reach naked eye visibly in the coming weeks, just as humanity braces its self in the midst of a global pandemic.

"I managed to photograph the comet approaching on Sunday evening through a small telescope.

"The comet has a similar orbit to the Great Comet of 1844, leading to speculation on whether C/2019 Y4 is a fragment of the same parent body."

The travelling space body is reported to only be a few kilometres wide but it's atmosphere has grown increasingly big, now believed to be about half as wide as the Sun.

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Comet coming towards the Earth caught on camera, and it's called C19 - MyLondon

Best Teams Ever bracket: WNBA edition, Round 2 – Yahoo Sports

Welcome to the Best Team Ever bracket series, where the greatest of all time have their most dominant seasons stacked up against each other until we ultimately crown a champion in each sport. The tournament will be decided by fan vote, so be sure to submit yours below! The results from the first round are here. The second round of polling closes at noon ET on Thursday, April 2.

[Brackets: NFL | NBA | MLB | NCAAF | NCAAB | NCAAW | WNBA | Soccer | NHL | Nascar]

Best Team Ever bracket series: WNBA edition, round 2 (Yahoo Sports illustration)

No. 1 Houston Comets (27-5)

OffRtg: 109.4 | DefRtg: 94.0 | Net: 18.4

The 2000 Comets, who cemented their dynasty status with a fourth title in four years, moved on easily with 87 percent of the vote over the 2005 Connecticut Sun in the 1-16 matchup. Sheryl Swoopes (20.7 PPG, 50.6 FG%) was named MVP and Defensive POY while 37-year-old Cynthia Cooper earned Finals MVP for a fourth time and the ESPY for best WNBA player. Tina Thompson (16.9 PPG, 41.7 3FT%) completed the first and continuously most celebrated big three in WNBA history.

The team scored 1.091 points per possession, which was the most efficient offense in WNBA history until the 2019 Washington Mystics. Their plus-12.8 point differential is best in league history and their nine 20-point wins rank second, again behind the 19 Mystics.

No. 9 Los Angeles Sparks (26-8)

OffRtg: 107.8 | DefRtg: 98.6 | Net: 9.2

The 2016 champion Sparks got by the 2012 Minnesota Lynx in the 8-9 matchup. That years Lynx squad had the fourth-best offensive rating in league history. Nneka Ogwumike was named league MVP, averaging 19.7 points on 66.5 percent shooting, 9.1 rebounds and 3.1 assists.

Candace Parker, a two-time MVP (08 13), averaged 19.3 points (49.6 FG%), 8.7 rebounds and 3.2 assists in the playoffs. Kristi Toliver, who signed a contract with the Sparks this offseason after the Mystics championship, had one of her best seasons averaging 13.2 points.

The overall teams effective field goal percentage (53.3) ranks third all-time.

No. 5 Seattle Storm (26-8)

OffRtg: 111.1 | DefRtg: 101.5 | Net: 9.6

League MVP Breanna Stewart, veteran Sue Bird

Rank top-10 in effective FG percentage

The 2018 Storm edged the 2013 Minnesota Lynx, which won their second championship, with 55 percent of the vote. Breanna Stewart had one of the most decorated 12 months in basketball history that included the 2018 WNBA championship alongside veteran Sue Bird. Their offensive rating ranks seventh and the teams effective field goal percentage (53.4) ranks second in league history. They also posted a top-10 assist-to-turnover ratio (1.58).

Stewart averaged 24.6 points in the playoffs and was joined in double-figures by Natasha Howard and Jewell Loyd. They swept the Mystics in the finals after a tough Game 5 win against the Mercurys big three of Diana Taurasi, Brittney Griner and DeWanna Bonner.

No. 4 Phoenix Mercury (29-5)

OffRtg: 106.4 | DefRtg: 94.1 | Net: 12.3

The 2014 Mercury won 71 percent of the vote against the 2016 Detroit Shock, which came back to win its second consecutive WNBA championship. Mercury Taurasi (16.2 PPG), Griner (15.6 PPG) and Bonner (10.4 PPG) led Phoenix to the 14 title. Griner, the No. 1 pick in the 2013 draft, was named the Defensive Player of the Year for her league-leading 153 blocks and the Mercury swept the Chicago Sky in the finals even though she missed Game 3.

Griner ranks third in career blocks (636) and Taurasi continues to add to her career lead in points (8,575). Their 2014 team lost only one game in the postseason (to the reigning champion Lynx) and lost only one of five games in the regular season by more than eight points.

Story continues

No. 15: Houston Comets (26-6)

OffRtg: 105.8 | DefRtg: 92.5 | Net: 13.3

The 1999 Houston Comets pulled the upset in a tough first-round matchup for the 2019 Washington Mystics, which hold a slew of WNBA records. The Comets advanced with 54 percent of the vote.

The Comets also had a season for the ages behind Cooper, Swoopes and Thompson. It was the third of their four championships and they beat opponents by an average of 9.3 points, ranking eighth. The 2000 and 1998 versions rank first and second, respectively.

No. 7 Los Angeles Sparks (28-4)

OffRtg: 106.7 | DefRtg: 94.7 | Net: 12.0

The 2001 Sparks advanced past the 2010 Storm, who had three-time MVP Lauren Jackson, with 67 percent of the vote in the first round.

Lisa Leslie won her first of three MVPs (2004, 06) averaging 19.5 points, 9.6 rebounds, 2.4 assists and 2.3 blocks. The Sparks lost four regular season games, three of which came in a streak in June and included two four-point losses. In the penultimate game, the margin was two. They dropped only one game in the playoffs, which were a best-of-three series then.

No. 6 Houston Comets (29-3)

OffRtg: 104.1 | DefRtg: 86.7 | Net: 17.4

Best win percentage in WNBA history (.900)

Rank second in point differential, net rating

The 1998 Houston Comets, arguably the second-best championship version behind the 2000 team, won 77 percent of the vote in the first round. They defeated the 2009 Mercury squad that featured regular-season and finals MVP Taurasi.

The Comets trail only the 2000 squad in point differential (12.8) and net rating (17.4), proving theyre one of the best all-around teams in league history. The team of course included the three Naismith Hall of Fame inductees of Cooper (22.7 PPG, 4.4 APG in 1998), Swoopes (15.6 PPG, 5.1 RPG)and Thompson (12.7 PPG, 7.1 RPG).

No. 3 Minnesota Lynx (27-7)

OffRtg: 108.5 | DefRtg: 94.4 | Net: 14.1

The 2017 Minnesota team is the only Lynx squad to make it through to the next round, getting 81 percent of the vote over the 2016 Chicago Sky. It was the last Lynx squad to win a championship, the final pillar in the dynasty that put them equal to the Comets with most WNBA titles (four).

The Lynx were another all-around quality squad, ranking sixth in offense and fourth in net rating differential. Sylvia Fowles was named the 2017 league MVP and both she and 14 MVP Maya Moore were named first-team All-WNBA selections. Rebekka Brunson was named to the second all-defensive team and Lindsey Whalen led the playoff offense, dishing out 4.9 assists per game.

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Best Teams Ever bracket: WNBA edition, Round 2 - Yahoo Sports

Newly-discovered comet Atlas could shine as bright as the MOON when it makes its closest approach to Earth in May – as long as doesn’t break up on its…

A comet called Atlas discovered in December is on its way towards Earth and could appear as bright as a crescent moon - unless it breaks up from the Sun's heat first.

Atlas is close to Mars' orbit at the moment but is increasing in speed as it makes its way towards the Sun, making its closest approach to Earth at the end of May.

It was discovered by the Asteroid Terrestrial-impact Last Alert system (ATLAS) in Hawaii and takes its name from the initials of the system.

When it was discovered on December 28, 2019 it was faint and required a telescope, but as it comes closer it is getting brighter and can now be seen with binoculars.

Seeing a comet with the naked eye would be a rare event for astronomers - the last bright comet in the northern hemisphere was Hale-Bopp in 1997.

Provided by Daily Mail This is an image of a comet captured by the Hubble Space Telescope - it is not ATLAS. If it manages to hold itself together ATLAS could be as bright as a a crescent moon

At the end of May it will be just 0.25 astronomical units to the Sun - that is a quarter of the distance the Earth is from the star.

While it is there it will get brighter as seen from the Earth as its glow will be amplified by the Sun.

'Comet ATLAS continues to brighten much faster than expected,' Karl Battams of the Naval Research Lab in Washington DC told SpaceWeatherArchive.

'Some predictions for its peak brightness now border on the absurd.'

It's original name was C/2019 Y4 when it was first discovered but has been nicknamed ATLAS due to the system that spotted it.

It has seen a 4,000-fold increase in brightness since it was first discovered and could be visible to the naked eye as early as April.

When it was first stopped it was in the area of Ursa Major and was very faint - it was about 398,000 times dimmer than stars visible to the naked eye appear.

At that point it was 273 million miles from the Sun but it has been increasing in brightness at an unprecedented speed since then.

Unfortunately there is a real chance it will break up from the heat before it gets a chance to put on a show for astronomers.

'Right now the comet is releasing huge amounts of its frozen volatiles (gases),' says Battams. 'That's why it's brightening so fast.'

The only way it will survive long enough to get as close to the Sun as Mercury it would need to have a large nuclear with stores of frozen gas.

If not it will likely 'run out of gas' leading to it crumbling and fading as it approaches the Sun, according to SpaceWeatherArchive.

Battams is not optimistic, though, he said it will likely break up.

'My personal intuition is that Comet ATLAS is over-achieving, and I wouldn't be surprised to see it start to fade rapidly and possibly even disintegrate before reaching the sun,' he says.

The head (or coma) of Comet ATLAS is big, albeit 'very faint and ghostly,' John Bortle, an expert in comets told Space.com.

'If it's a truly significant visitor, it should be considerably sharper in appearance. Instead we see, at best, a quite modestly condensed object with only a pinpoint stellar feature near its heart.'

If it does break up as it approaches the Sun it may still be possible for NASA spacecraft to capture images of the end of its life.

'The Heliospheric Imager on NASA's STEREO spacecraft will get a great view of ATLAS from mid-May through early June,' says Battams.

'The camera is very sensitive, so we might be able to observe ATLAS's tail interacting with the solar wind and outflowsas well as any potential breakup events.'

There is some speculation this could be related to the Great Comet of 1844 as it follows a similar trajectory and orbit.

Its trajectory would require a 6,000 year orbit around the Sun that would take it beyond the outer edges of the solar system - about 57 billion miles from the Sun.

Astronomers predict this comet and the Great Comet both broke off from a much larger comet born in the early days of the solar system.

It's a hyperbolic comet which means its orbit stretches deeper into the cosmos and the Sun only acts as a gravitational slingshot to hurtle it further out of the solar system.

This may be a one time shot - we may never see the comet again after it makes its closest approach.

In the meantime when it gets dark it will be visible halfway up in the north-northwest sky and potentially visible with the naked eye from April.

'It's going to be fun the next few weeks watching Comet ATLAS develop (and provide a nice distraction from the current state of the world), Carl Hergenrother, a comet observer based in Arizona, wrote. 'Here's to good health and clear skies!'

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Newly-discovered comet Atlas could shine as bright as the MOON when it makes its closest approach to Earth in May - as long as doesn't break up on its...

comet | Definition, Composition, & Facts | Britannica

Comets are among the most-spectacular objects in the sky, with their bright glowing comae and their long dust tails and ion tails. Comets can appear at random from any direction and provide a fabulous and ever-changing display for many months as they move in highly eccentric orbits around the Sun.

Comets are important to scientists because they are primitive bodies left over from the formation of the solar system. They were among the first solid bodies to form in the solar nebula, the collapsing interstellar cloud of dust and gas out of which the Sun and planets formed. Comets formed in the outer regions of the solar nebula where it was cold enough for volatile ices to condense. This is generally taken to be beyond 5 astronomical units (AU; 748 million km, or 465 million miles), or beyond the orbit of Jupiter. Because comets have been stored in distant orbits beyond the planets, they have undergone few of the modifying processes that have melted or changed the larger bodies in the solar system. Thus, they retain a physical and chemical record of the primordial solar nebula and of the processes involved in the formation of planetary systems.

A comet is made up of four visible parts: the nucleus, the coma, the ion tail, and the dust tail. The nucleus is a solid body typically a few kilometres in diameter and made up of a mixture of volatile ices (predominantly water ice) and silicate and organic dust particles. The coma is the freely escaping atmosphere around the nucleus that forms when the comet comes close to the Sun and the volatile ices sublimate, carrying with them dust particles that are intimately mixed with the frozen ices in the nucleus. The dust tail forms from those dust particles and is blown back by solar radiation pressure to form a long curving tail that is typically white or yellow in colour. The ion tail forms from the volatile gases in the coma when they are ionized by ultraviolet photons from the Sun and blown away by the solar wind. Ion tails point almost exactly away from the Sun and glow bluish in colour because of the presence of CO+ ions.

Comets differ from other bodies in the solar system in that they are generally in orbits that are far more eccentric than those of the planets and most asteroids and far more inclined to the ecliptic (the plane of Earths orbit). Some comets appear to come from distances of over 50,000 AU, a substantial fraction of the distance to the nearest stars. Their orbital periods can be millions of years in length. Other comets have shorter periods and smaller orbits that carry them from the orbits of Jupiter and Saturn inward to the orbits of the terrestrial planets. Some comets even appear to come from interstellar space, passing around the Sun on open, hyperbolic orbits, but in fact are members of the solar system.

Comets are typically named for their discoverers, though some comets (e.g., Halley and Encke) are named for the scientists who first recognized that their orbits were periodic. The International Astronomical Union (IAU) prefers a maximum of two discoverers to be in a comets name. In some cases where a comet has been lost (its orbit was not determined well enough to predict its return), the comet is named for the original discoverer and also the observer(s) who found it again. A designation of C/ before a comets name denotes that it is a long-period comet (period greater than 200 years), while P/ denotes that the comet is periodic; i.e., it returns at regular, predictable intervals of fewer than 200 years. A designation of D/ denotes that the comet is deceased or destroyed, such as D/Shoemaker-Levy 9, the comet whose components struck Jupiter in July 1994. Numbers appearing before the name of a comet denote that it is periodic; the comets are numbered in the order that they are confirmed to be periodic. Comet 1P/Halley is the first comet to be recognized as periodic and is named after English astronomer Edmond Halley, who determined that it was periodic.

In 1995 the IAU implemented a new identification system for each appearance of a comet, whether it is periodic or long-period. The system uses the year of the comets discovery, the half-month in the year denoted by a letter A through Y (with I omitted to avoid confusion), and a number signifying the order in which the comet was found within that half-month. Thus, Halleys Comet is designated 1P/1682 Q1 when Halley saw it in August 1682, but 1P/1982 U1 when it was first spotted by astronomers before its predicted perihelion (point when closest to the Sun) passage in 1986. This identification system is similar to that now used for asteroid discoveries, though the asteroids are so designated only when they are first discovered. (The asteroids are later given official catalog numbers and names.) Formerly, a number after the name of a periodic comet denoted its order among comets discovered by that individual or group, but for new comets there would be no such distinguishing number.

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comet | Definition, Composition, & Facts | Britannica

What Are Comets? – Time and Date

Comets are small celestial bodies that orbit the Sun. Primarily made of dust and ice, they are thought to be remnants of the formation of the Solar System.

Comet PanSTARRS was visible in early 2013.

Comet PanSTARRS C/2011 L4 was visible to observers on Earth in early 2013.

thinkstockphoto.com

Comets are thought to come from 2 places in the Solar System:

What are meteor showers?

One of the distinguishing features of a comet is that most of them develop a tail, known as a coma, when they come close to the Sun.

Away from the Sun, comets are frozen celestial bodies that are hard to detect. However, as a comet comes closer to the Sun, the Suns heat and radiation vaporize the ice and dust of the comet. These vaporized gasses collect dust and stream out of the center of the comet like a tail. This tail can be thousands of miles long.

While most comets passing by the Sun are hard to observe from Earth without specialized equipment, some comets are bright enough to be seen by the naked eye. The brightness of the comet is due to sunlight reflecting and refracting off the dust in the tail.

Comets usually have 2 tails, which point in different directions. The dust in the comet is responsible for one tail. This tail, also called the dust tail, tends to be broad and curved. The gasses in the comet make the second tail, called the plasma or the ion tail. This tail is thin and straight and tends to point directly away from the Sun.

What are asteroids?

A light year (light-year or lightyear) is a unit of distance and is defined by the International Astronomical Union as the distance traveled by light in a vacuum during a Julian year. It is approximately equal to 10 trillion kilometers (6 trillion miles).

Topics: Astronomy, Comets, Asteroids

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What Are Comets? - Time and Date

Comets: Facts About The ‘Dirty Snowballs’ of Space | Space

Comets are icy bodies in space that release gas or dust. They are often compared to dirty snowballs, though recent research has led some scientists to call them snowy dirtballs. Comets contain dust, ice, carbon dioxide, ammonia, methane and more. Astronomers think comets are leftovers from the material that initially formed the solar system about 4.6 billion years ago.

Some researchers think comets might have originally brought some of the water and organic molecules to Earth that now make up life here. To research this hypothesis, the Rosetta mission, which landed a probe on a comet on Nov. 12, 2014, is studying its nucleus and environment, observing how it changes as it approaches the sun.

Comets orbit the sun, but most are believed to inhabit in an area known as the Oort Cloud, far beyond the orbit of Pluto. Occasionally a comet streaks through the inner solar system; some do so regularly, some only once every few centuries. Many people have never seen a comet, but those who have won't easily forget the celestial show.

The solid nucleus or core of a comet consists mostly of ice and dust coated with dark organic material, according to NASA, with the ice composed mainly of frozen water but perhaps other frozen substances as well, such as ammonia, carbon dioxide, carbon monoxide and methane. The nucleus may have a small rocky core.

As a comet gets closer to the sun, the ice on the surface of the nucleus begins turning into gas, forming a cloud known as the coma. Radiation from the sun pushes dust particles away from the coma, forming a dust tail, while charged particles from the sun convert some of the comet's gases into ions, forming an ion tail. Since comet tails are shaped by sunlight and the solar wind, they always point away from the sun. Comet tails may spray planets, as was the case in 2013 with Comet Siding Spring and Mars.

At first glance, comets and asteroids may appear very similar. The difference lies in the presence of the coma and tail. Sometimes, a comet may be misidentified as an asteroid before follow-up observations reveal the presence of either or both of these features.

The nuclei of most comets are thought to measure 10 miles (16 kilometers) or less. Some comets have comas that can reach nearly 1 million miles (1.6 million km) wide, and some have tails reaching 100 million miles (160 million km) long.

We can see a number of comets with the naked eye when they pass close to the sun because their comas and tails reflect sunlight or even glow because of energy they absorb from the sun. However, most comets are too small or too faint to be seen without a telescope.

Comets leave a trail of debris behind them that can lead to meteor showers on Earth. For instance, the Perseid meteor shower occurs every year between August 9 and 13 when Earth passes through the orbit of the Swift-Tuttle comet.

Astronomers classify comets based on the durations of their orbits around the sun. Short-period comets need roughly 200 years or less to complete one orbit, long-period comets take more than 200 years, and single-apparition comets are not bound to the sun, on orbits that take them out of the solar system, according to NASA. Recently, scientists have also discovered comets in the main asteroid belt these main-belt comets might be a key source of water for the inner terrestrial planets.

Scientists think short-period comets, also known as periodic comets, originate from a disk-shaped band of icy objects known as the Kuiper Belt beyond Neptune's orbit, with gravitational interactions with the outer planets dragging these bodies inward, where they become active comets. Long-period comets are thought to come from the nearly spherical Oort Cloud even further out, which get slung inward by the gravitational pull of passing stars. In 2017, scientists found there may be seven times more big long-period comets than previously thought.

Some comets, called sun-grazers, smash right into the sun or get so close that they break up and evaporate. Some researchers are also concerned that comets may pose a threat to Earth as well.

In general, comets are named after their discoverer. For example, comet Shoemaker-Levy 9 got its name because it was the ninth short-periodic comet discovered by Eugene and Carolyn Shoemaker and David Levy. Spacecraft have proven very effective at spotting comets as well, so the names of many comets incorporate the names of missions such as SOHO or WISE.

In antiquity, comets inspired both awe and alarm, "hairy stars" resembling fiery swords that appeared unpredictably in the sky. Often, comets seemed to be omens of doom the most ancient known mythology, the Babylonian "Epic of Gilgamesh," described fire, brimstone, and flood with the arrival of a comet, and the Roman emperor Nero saved himself from the "curse of the comet" by having all possible successors to his throne executed. This fear was not just limited to the distant past in 1910, people in Chicago sealed their windows to protect themselves from what they thought was the comet's poisonous tail.

For centuries, scientists thought comets traveled in the Earth's atmosphere, but in 1577, observations made by Danish astronomer Tycho Brahe revealed they actually traveled far beyond the moon. Isaac Newton later discovered that comets move in elliptical, oval-shaped orbits around the sun, and correctly predicted that they could return again and again.

Chinese astronomers kept extensive records on comets for centuries, including observations of Halley's Comet going back to at least 240 B.C., historic annals that have proven valuable resources for later astronomers.

A number of recent missions have ventured to comets. NASA's Deep Impact collided an impactor into Comet Tempel 1 in 2005 and recorded the dramatic explosion that revealed the interior composition and structure of the nucleus. In 2009, NASA announced samples the Stardust mission returned from Comet Wild 2 revealed a building block of life.

In 2014, the European Space Agency's Rosetta spacecraft entered orbit around Comet 67P/Churyumov-Gerasimenko. The Philae lander touched down on Nov 12, 2014. Among the Rosetta mission's many discoveries was the first detection of organic molecules on the surface of a comet; a strange song from Comet 67P/Churyumov-Gerasimenko; the possibilities that the comet's odd shape may be due to it spinning apart, or resulting from two comets fusing together; and the fact that comets may possess hard, crispy outsides and cold but soft insides, just like fried ice cream. On Sept. 30, 2016, Rosetta intentionally crash-landed on the comet, ending its mission.

Halley's Comet is likely the most famous comet in the world, even depicted in the Bayeux Tapestry that chronicled the Battle of Hastings of 1066. It becomes visible to the naked eye every 76 years when it nears the sun. When Halley's Comet zoomed near Earth in 1986, five spacecraft flew past it and gathered unprecedented details, coming close enough to study its nucleus, which is normally concealed by the comet's coma. The roughly potato-shaped, 9-mile-long (15 km) comet contains equal parts ice and dust, with some 80 percent of the ice made of water and about 15 percent of it consisting of frozen carbon monoxide. Researchers believe other comets are chemically similar to Halley's Comet. The nucleus of Halley's Comet was unexpectedly extremely dark black its surface, and perhaps those of most others, is apparently covered with a black crust of dust over most of the ice, and it only releases gas when holes in this crust expose ice to the sun.

The comet Shoemaker-Levy 9 collided spectacularly with Jupiter in 1994, with the giant planet's gravitational pull ripping the comet apart for at least 21 visible impacts. The largest collision created a fireball that rose about 1,800 miles (3,000 km) above the Jovian cloud tops as well as a giant dark spot more than 7,460 miles (12,000 km) across about the size of the Earth and was estimated to have exploded with the force of 6,000 gigatons of TNT.

A recent, highly visible comet was Hale-Bopp, which came within 122 million miles (197 million km) of Earth in 1997. Its unusually large nucleus gave off a great deal of dust and gas estimated at roughly 18 to 25 miles (30 to 40 km) across appeared bright to the naked eye.

Comet ISON was expected to give a spectacular show in 2013. However, the sun-grazer did not survive its close encounter with the sun and was destroyed in December.

Additional reporting by Nola Taylor Redd, Space.com contributor

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Comets: Facts About The 'Dirty Snowballs' of Space | Space

Comet – Wikipedia

A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena are due to the effects of solar radiation and the solar wind acting upon the nucleus of the comet. Comet nuclei range from a few hundred meters to tens of kilometers across and are composed of loose collections of ice, dust, and small rocky particles. The coma may be up to 15 times Earth's diameter, while the tail may stretch one astronomical unit. If sufficiently bright, a comet may be seen from Earth without the aid of a telescope and may subtend an arc of 30 (60 Moons) across the sky. Comets have been observed and recorded since ancient times by many cultures.

Comets usually have highly eccentric elliptical orbits, and they have a wide range of orbital periods, ranging from several years to potentially several millions of years. Short-period comets originate in the Kuiper belt or its associated scattered disc, which lie beyond the orbit of Neptune. Long-period comets are thought to originate in the Oort cloud, a spherical cloud of icy bodies extending from outside the Kuiper belt to halfway to the nearest star.[1] Long-period comets are set in motion towards the Sun from the Oort cloud by gravitational perturbations caused by passing stars and the galactic tide. Hyperbolic comets may pass once through the inner Solar System before being flung to interstellar space. The appearance of a comet is called an apparition.

Comets are distinguished from asteroids by the presence of an extended, gravitationally unbound atmosphere surrounding their central nucleus. This atmosphere has parts termed the coma (the central part immediately surrounding the nucleus) and the tail (a typically linear section consisting of dust or gas blown out from the coma by the Sun's light pressure or outstreaming solar wind plasma). However, extinct comets that have passed close to the Sun many times have lost nearly all of their volatile ices and dust and may come to resemble small asteroids.[2] Asteroids are thought to have a different origin from comets, having formed inside the orbit of Jupiter rather than in the outer Solar System.[3][4] The discovery of main-belt comets and active centaur minor planets has blurred the distinction between asteroids and comets. In the early 21st century, the discovery of some minor bodies with long-period comet orbits, but characteristics of inner solar system asteroids, were called Manx comets. They are still classified as comets, such as C/2014 S3 (PANSTARRS).[5] 27 Manx comets were found from 2013 to 2017.[6]

As of July2019[update] there are 6,619 known comets,[7] a number that is steadily increasing as they are discovered. However, this represents only a tiny fraction of the total potential comet population, as the reservoir of comet-like bodies in the outer Solar System (in the Oort cloud) is estimated to be one trillion.[8][9] Roughly one comet per year is visible to the naked eye, though many of those are faint and unspectacular.[10] Particularly bright examples are called "great comets". Comets have been visited by unmanned probes such as the European Space Agency's Rosetta, which became the first to land a robotic spacecraft on a comet,[11] and NASA's Deep Impact, which blasted a crater on Comet Tempel 1 to study its interior.

The word comet derives from the Old English cometa from the Latin comta or comts. That, in turn, is a latinization of the Greek ("wearing long hair"), and the Oxford English Dictionary notes that the term () already meant "long-haired star, comet" in Greek. was derived from ("to wear the hair long"), which was itself derived from ("the hair of the head") and was used to mean "the tail of a comet".[12][13]

The astronomical symbol for comets is (in Unicode U+2604), consisting of a small disc with three hairlike extensions.[14]

The solid, core structure of a comet is known as the nucleus. Cometary nuclei are composed of an amalgamation of rock, dust, water ice, and frozen carbon dioxide, carbon monoxide, methane, and ammonia.[15] As such, they are popularly described as "dirty snowballs" after Fred Whipple's model.[16] However, many comets have a higher dust content, leading them to be called "icy dirtballs".[17] The term "icy dirtballs" arose after observation of Comet 9P/Tempel 1 collision with an "impactor" probe sent by NASA Deep Impact mission in July 2005. Research conducted in 2014 suggests that comets are like "deep fried ice cream", in that their surfaces are formed of dense crystalline ice mixed with organic compounds, while the interior ice is colder and less dense.[18]

The surface of the nucleus is generally dry, dusty or rocky, suggesting that the ices are hidden beneath a surface crust several metres thick. In addition to the gases already mentioned, the nuclei contain a variety of organic compounds, which may include methanol, hydrogen cyanide, formaldehyde, ethanol, ethane, and perhaps more complex molecules such as long-chain hydrocarbons and amino acids.[19][20] In 2009, it was confirmed that the amino acid glycine had been found in the comet dust recovered by NASA's Stardust mission.[21] In August 2011, a report, based on NASA studies of meteorites found on Earth, was published suggesting DNA and RNA components (adenine, guanine, and related organic molecules) may have been formed on asteroids and comets.[22][23]

The outer surfaces of cometary nuclei have a very low albedo, making them among the least reflective objects found in the Solar System. The Giotto space probe found that the nucleus of Halley's Comet reflects about four percent of the light that falls on it,[24] and Deep Space 1 discovered that Comet Borrelly's surface reflects less than 3.0%;[24] by comparison, asphalt reflects seven percent. The dark surface material of the nucleus may consist of complex organic compounds. Solar heating drives off lighter volatile compounds, leaving behind larger organic compounds that tend to be very dark, like tar or crude oil. The low reflectivity of cometary surfaces causes them to absorb the heat that drives their outgassing processes.[25]

Comet nuclei with radii of up to 30 kilometers (19mi) have been observed,[26] but ascertaining their exact size is difficult.[27] The nucleus of 322P/SOHO is probably only 100200 meters (330660ft) in diameter.[28] A lack of smaller comets being detected despite the increased sensitivity of instruments has led some to suggest that there is a real lack of comets smaller than 100 meters (330ft) across.[29] Known comets have been estimated to have an average density of 0.6g/cm3 (0.35oz/cuin).[30] Because of their low mass, comet nuclei do not become spherical under their own gravity and therefore have irregular shapes.[31]

Roughly six percent of the near-Earth asteroids are thought to be extinct nuclei of comets that no longer experience outgassing,[32] including 14827 Hypnos and 3552 Don Quixote.

Results from the Rosetta and Philae spacecraft show that the nucleus of 67P/ChuryumovGerasimenko has no magnetic field, which suggests that magnetism may not have played a role in the early formation of planetesimals.[33][34] Further, the ALICE spectrograph on Rosetta determined that electrons (within 1km (0.62mi) above the comet nucleus) produced from photoionization of water molecules by solar radiation, and not photons from the Sun as thought earlier, are responsible for the degradation of water and carbon dioxide molecules released from the comet nucleus into its coma.[35][36] Instruments on the Philae lander found at least sixteen organic compounds at the comet's surface, four of which (acetamide, acetone, methyl isocyanate and propionaldehyde) have been detected for the first time on a comet.[37][38][39]

The streams of dust and gas thus released form a huge and extremely thin atmosphere around the comet called the "coma". The force exerted on the coma by the Sun's radiation pressure and solar wind cause an enormous "tail" to form pointing away from the Sun.[48]

The coma is generally made of H2O and dust, with water making up to 90% of the volatiles that outflow from the nucleus when the comet is within 3 to 4 astronomical units (450,000,000 to 600,000,000km; 280,000,000 to 370,000,000mi) of the Sun.[49] The H2O parent molecule is destroyed primarily through photodissociation and to a much smaller extent photoionization, with the solar wind playing a minor role in the destruction of water compared to photochemistry.[49] Larger dust particles are left along the comet's orbital path whereas smaller particles are pushed away from the Sun into the comet's tail by light pressure.[50]

Although the solid nucleus of comets is generally less than 60 kilometers (37mi) across, the coma may be thousands or millions of kilometers across, sometimes becoming larger than the Sun.[51] For example, about a month after an outburst in October 2007, comet 17P/Holmes briefly had a tenuous dust atmosphere larger than the Sun.[52] The Great Comet of 1811 also had a coma roughly the diameter of the Sun.[53] Even though the coma can become quite large, its size can decrease about the time it crosses the orbit of Mars around 1.5 astronomical units (220,000,000km; 140,000,000mi) from the Sun.[53] At this distance the solar wind becomes strong enough to blow the gas and dust away from the coma, and in doing so enlarging the tail.[53] Ion tails have been observed to extend one astronomical unit (150million km) or more.[52]

Both the coma and tail are illuminated by the Sun and may become visible when a comet passes through the inner Solar System, the dust reflects sunlight directly while the gases glow from ionisation.[54] Most comets are too faint to be visible without the aid of a telescope, but a few each decade become bright enough to be visible to the naked eye.[55] Occasionally a comet may experience a huge and sudden outburst of gas and dust, during which the size of the coma greatly increases for a period of time. This happened in 2007 to Comet Holmes.[56]

In 1996, comets were found to emit X-rays.[57] This greatly surprised astronomers because X-ray emission is usually associated with very high-temperature bodies. The X-rays are generated by the interaction between comets and the solar wind: when highly charged solar wind ions fly through a cometary atmosphere, they collide with cometary atoms and molecules, "stealing" one or more electrons from the atom in a process called "charge exchange". This exchange or transfer of an electron to the solar wind ion is followed by its de-excitation into the ground state of the ion by the emission of X-rays and far ultraviolet photons.[58]

Bow shocks form as a result of the interaction between the solar wind and the cometary ionosphere, which is created by ionization of gases in the coma. As the comet approaches the Sun, increasing outgassing rates cause the coma to expand, and the sunlight ionizes gases in the coma. When the solar wind passes through this ion coma, the bow shock appears.

The first observations were made in the 1980s and 90s as several spacecraft flew by comets 21P/GiacobiniZinner,[59] 1P/Halley,[60] and 26P/GriggSkjellerup.[61] It was then found that the bow shocks at comets are wider and more gradual than the sharp planetary bow shocks seen at, for example, Earth. These observations were all made near perihelion when the bow shocks already were fully developed.

The Rosetta spacecraft observed the bow shock at comet 67P/ChuryumovGerasimenko at an early stage of bow shock development when the outgassing increased during the comet's journey toward the Sun. This young bow shock was called the "infant bow shock". The infant bow shock is asymmetric and, relative to the distance to the nucleus, wider than fully developed bow shocks.[62]

In the outer Solar System, comets remain frozen and inactive and are extremely difficult or impossible to detect from Earth due to their small size. Statistical detections of inactive comet nuclei in the Kuiper belt have been reported from observations by the Hubble Space Telescope[63][64] but these detections have been questioned.[65][66] As a comet approaches the inner Solar System, solar radiation causes the volatile materials within the comet to vaporize and stream out of the nucleus, carrying dust away with them.

The streams of dust and gas each form their own distinct tail, pointing in slightly different directions. The tail of dust is left behind in the comet's orbit in such a manner that it often forms a curved tail called the type II or dust tail.[54] At the same time, the ion or type I tail, made of gases, always points directly away from the Sun because this gas is more strongly affected by the solar wind than is dust, following magnetic field lines rather than an orbital trajectory.[67] On occasionssuch as when Earth passes through a comet's orbital plane, the antitail, pointing in the opposite direction to the ion and dust tails, may be seen.[68]

The observation of antitails contributed significantly to the discovery of solar wind.[69] The ion tail is formed as a result of the ionization by solar ultra-violet radiation of particles in the coma. Once the particles have been ionized, they attain a net positive electrical charge, which in turn gives rise to an "induced magnetosphere" around the comet. The comet and its induced magnetic field form an obstacle to outward flowing solar wind particles. Because the relative orbital speed of the comet and the solar wind is supersonic, a bow shock is formed upstream of the comet in the flow direction of the solar wind. In this bow shock, large concentrations of cometary ions (called "pick-up ions") congregate and act to "load" the solar magnetic field with plasma, such that the field lines "drape" around the comet forming the ion tail.[70]

If the ion tail loading is sufficient, the magnetic field lines are squeezed together to the point where, at some distance along the ion tail, magnetic reconnection occurs. This leads to a "tail disconnection event".[70] This has been observed on a number of occasions, one notable event being recorded on 20 April 2007, when the ion tail of Encke's Comet was completely severed while the comet passed through a coronal mass ejection. This event was observed by the STEREO space probe.[71]

In 2013, ESA scientists reported that the ionosphere of the planet Venus streams outwards in a manner similar to the ion tail seen streaming from a comet under similar conditions."[72][73]

Uneven heating can cause newly generated gases to break out of a weak spot on the surface of comet's nucleus, like a geyser.[74] These streams of gas and dust can cause the nucleus to spin, and even split apart.[74] In 2010 it was revealed dry ice (frozen carbon dioxide) can power jets of material flowing out of a comet nucleus.[75] Infrared imaging of Hartley2 shows such jets exiting and carrying with it dust grains into the coma.[76]

Most comets are small Solar System bodies with elongated elliptical orbits that take them close to the Sun for a part of their orbit and then out into the further reaches of the Solar System for the remainder.[77] Comets are often classified according to the length of their orbital periods: The longer the period the more elongated the ellipse.

Periodic comets or short-period comets are generally defined as those having orbital periods of less than 200 years.[78] They usually orbit more-or-less in the ecliptic plane in the same direction as the planets.[79] Their orbits typically take them out to the region of the outer planets (Jupiter and beyond) at aphelion; for example, the aphelion of Halley's Comet is a little beyond the orbit of Neptune. Comets whose aphelia are near a major planet's orbit are called its "family".[80] Such families are thought to arise from the planet capturing formerly long-period comets into shorter orbits.[81]

At the shorter orbital period extreme, Encke's Comet has an orbit that does not reach the orbit of Jupiter, and is known as an Encke-type comet. Short-period comets with orbital periods less than 20 years and low inclinations (up to 30 degrees) to the ecliptic are called traditional Jupiter-family comets (JFCs).[82][83] Those like Halley, with orbital periods of between 20 and 200 years and inclinations extending from zero to more than 90 degrees, are called Halley-type comets (HTCs).[84][85] As of 2019[update], 89 HTCs have been observed,[86] compared with 676 identified JFCs.[87]

Recently discovered main-belt comets form a distinct class, orbiting in more circular orbits within the asteroid belt.[88]

Because their elliptical orbits frequently take them close to the giant planets, comets are subject to further gravitational perturbations.[89] Short-period comets have a tendency for their aphelia to coincide with a giant planet's semi-major axis, with the JFCs being the largest group.[83] It is clear that comets coming in from the Oort cloud often have their orbits strongly influenced by the gravity of giant planets as a result of a close encounter. Jupiter is the source of the greatest perturbations, being more than twice as massive as all the other planets combined. These perturbations can deflect long-period comets into shorter orbital periods.[90][91]

Based on their orbital characteristics, short-period comets are thought to originate from the centaurs and the Kuiper belt/scattered disc[92] a disk of objects in the trans-Neptunian regionwhereas the source of long-period comets is thought to be the far more distant spherical Oort cloud (after the Dutch astronomer Jan Hendrik Oort who hypothesized its existence).[93] Vast swarms of comet-like bodies are thought to orbit the Sun in these distant regions in roughly circular orbits. Occasionally the gravitational influence of the outer planets (in the case of Kuiper belt objects) or nearby stars (in the case of Oort cloud objects) may throw one of these bodies into an elliptical orbit that takes it inwards toward the Sun to form a visible comet. Unlike the return of periodic comets, whose orbits have been established by previous observations, the appearance of new comets by this mechanism is unpredictable.[94] When flung into the orbit of the sun, and being continuously dragged towards it, tons of matter are stripped from the comets which greatly influence their lifetime; the more stripped, the shorter they live and vice versa.[95]

Long-period comets have highly eccentric orbits and periods ranging from 200 years to thousands of years.[96] An eccentricity greater than 1 when near perihelion does not necessarily mean that a comet will leave the Solar System.[97] For example, Comet McNaught had a heliocentric osculating eccentricity of 1.000019 near its perihelion passage epoch in January 2007 but is bound to the Sun with roughly a 92,600-year orbit because the eccentricity drops below 1 as it moves farther from the Sun. The future orbit of a long-period comet is properly obtained when the osculating orbit is computed at an epoch after leaving the planetary region and is calculated with respect to the center of mass of the Solar System. By definition long-period comets remain gravitationally bound to the Sun; those comets that are ejected from the Solar System due to close passes by major planets are no longer properly considered as having "periods". The orbits of long-period comets take them far beyond the outer planets at aphelia, and the plane of their orbits need not lie near the ecliptic. Long-period comets such as Comet West and C/1999 F1 can have aphelion distances of nearly 70,000 AU with orbital periods estimated around 6 million years.

Single-apparition or non-periodic comets are similar to long-period comets because they also have parabolic or slightly hyperbolic trajectories[96] when near perihelion in the inner Solar System. However, gravitational perturbations from giant planets cause their orbits to change. Single-apparition comets have a hyperbolic or parabolic osculating orbit which allows them to permanently exit the Solar System after a single pass of the Sun.[98] The Sun's Hill sphere has an unstable maximum boundary of 230,000AU (1.1pc; 3.6ly).[99] Only a few hundred comets have been seen to reach a hyperbolic orbit (e > 1) when near perihelion[100] that using a heliocentric unperturbed two-body best-fit suggests they may escape the Solar System.

As of 2019[update], only two objects have been discovered with an eccentricity significantly greater than one: 1I/Oumuamua and 2I/Borisov, indicating an origin outside the Solar System. While Oumuamua, with an eccentricity of about 1.2, showed no optical signs of cometary activity during its passage through the inner Solar System in October 2017, changes to its trajectorywhich suggests outgassingindicate that it is probably a comet.[101] On the other hand, 2I/Borisov, with an estimated eccentricity of about 3.36, has been observed to have the coma feature of comets, and is considered the first detected interstellar comet.[102][103] Comet C/1980 E1 had an orbital period of roughly 7.1million years before the 1982 perihelion passage, but a 1980 encounter with Jupiter accelerated the comet giving it the largest eccentricity (1.057) of any known hyperbolic comet.[104] Comets not expected to return to the inner Solar System include C/1980 E1, C/2000 U5, C/2001 Q4 (NEAT), C/2009 R1, C/1956 R1, and C/2007 F1 (LONEOS).

Some authorities use the term "periodic comet" to refer to any comet with a periodic orbit (that is, all short-period comets plus all long-period comets),[105] whereas others use it to mean exclusively short-period comets.[96] Similarly, although the literal meaning of "non-periodic comet" is the same as "single-apparition comet", some use it to mean all comets that are not "periodic" in the second sense (that is, to also include all comets with a period greater than 200 years).

Early observations have revealed a few genuinely hyperbolic (i.e. non-periodic) trajectories, but no more than could be accounted for by perturbations from Jupiter. If comets pervaded interstellar space, they would be moving with velocities of the same order as the relative velocities of stars near the Sun (a few tens of km per second). If such objects entered the Solar System, they would have positive specific orbital energy and would be observed to have genuinely hyperbolic trajectories. A rough calculation shows that there might be four hyperbolic comets per century within Jupiter's orbit, give or take one and perhaps two orders of magnitude.[106]

The Oort cloud is thought to occupy a vast space starting from between 2,000 and 5,000AU (0.03 and 0.08ly)[108] to as far as 50,000AU (0.79ly)[84] from the Sun. This cloud encases the celestial bodies that start at the middle of our solar systemthe sun, all the way to outer limits of the Kuiper Belt. The Oort cloud consists of viable materials necessary for the creation of celestial bodies. The planets we have today, exist only because of the planetesimals (chunks of leftover space that assisted in the creation of planets) that were condensed and formed by the gravity of the sun. The eccentric made from these trapped planetesimals is why the Oort Cloud even exists.[109] Some estimates place the outer edge at between 100,000 and 200,000AU (1.58 and 3.16ly).[108] The region can be subdivided into a spherical outer Oort cloud of 20,00050,000AU (0.320.79ly), and a doughnut-shaped inner cloud, the Hills cloud, of 2,00020,000AU (0.030.32ly).[110] The outer cloud is only weakly bound to the Sun and supplies the long-period (and possibly Halley-type) comets that fall to inside the orbit of Neptune.[84] The inner Oort cloud is also known as the Hills cloud, named after J. G. Hills, who proposed its existence in 1981.[111] Models predict that the inner cloud should have tens or hundreds of times as many cometary nuclei as the outer halo;[111][112][113] it is seen as a possible source of new comets that resupply the relatively tenuous outer cloud as the latter's numbers are gradually depleted. The Hills cloud explains the continued existence of the Oort cloud after billions of years.[114]

Exocomets beyond the Solar System have also been detected and may be common in the Milky Way.[115] The first exocomet system detected was around a star named Beta Pictoris, a very young sitting at around 20 million years old A-type main-sequence star, in 1987.[116][117] A total of 11 such exocomet systems have been identified as of 2013[update], using the absorption spectrum caused by the large clouds of gas emitted by comets when passing close to their star.[115][116] For ten years the Kepler Space Telescope was responsible for searching for planets and other forms outside of the solar system. The first transiting exocomets were found in February 2018 by a group consisting of professional astronomers and citizen scientists in light curves recorded by the Kepler Space Telescope.[118][119] After Kepler Space Telescope retired in October 2018, a new telescope called TESS Telescope has taken over Kepler's mission. Since the launch of TESS, astronomers have discovered the transits of comets around the star Beta Pictoris using a light curve from TESS.[120][121] Since TESS has taken over, astronomers have since been able to better distinguish exocomets with the spectroscopic method. New planets are detected by the white light curve method which is viewed as a symmetrical dip in the charts readings when a planet overshadows its parent star. However, after further evaluation of these light curves, it has been discovered that the asymmetrical patterns of the dips presented are caused by the tail of a comet or of hundreds of comets.[122]

As a comet is heated during close passes to the Sun, outgassing of its icy components also releases solid debris too large to be swept away by radiation pressure and the solar wind.[123] If Earth's orbit sends it through that trail of debris, which is composed mostly of fine grains of rocky material, there is likely to be a meteor shower as Earth passes through. Denser trails of debris produce quick but intense meteor showers and less dense trails create longer but less intense showers. Typically, the density of the debris trail is related to how long ago the parent comet released the material.[124][125] The Perseid meteor shower, for example, occurs every year between 9 and 13 August, when Earth passes through the orbit of Comet SwiftTuttle. Halley's Comet is the source of the Orionid shower in October.[126][127]

Many comets and asteroids collided with Earth in its early stages. Many scientists think that comets bombarding the young Earth about 4billion years ago brought the vast quantities of water that now fill Earth's oceans, or at least a significant portion of it. Others have cast doubt on this idea.[128] The detection of organic molecules, including polycyclic aromatic hydrocarbons,[18] in significant quantities in comets has led to speculation that comets or meteorites may have brought the precursors of lifeor even life itselfto Earth.[129] In 2013 it was suggested that impacts between rocky and icy surfaces, such as comets, had the potential to create the amino acids that make up proteins through shock synthesis.[130] The speed at which the comets entered the atmosphere, combined with the magnitude of energy created after initial contact, allowed smaller molecules to condense into the larger macro-molecules that served as the foundation for life.[131] In 2015, scientists found significant amounts of molecular oxygen in the outgassings of comet 67P, suggesting that the molecule may occur more often than had been thought, and thus less an indicator of life as has been supposed.[132]

It is suspected that comet impacts have, over long timescales, also delivered significant quantities of water to Earth's Moon, some of which may have survived as lunar ice.[133] Comet and meteoroid impacts are also thought to be responsible for the existence of tektites and australites.[134]

Fear of comets as acts of God and signs of impending doom was highest in Europe from AD 1200 to 1650.[135] The year after the Great Comet of 1618, for example, Gotthard Arthusius published a pamphlet stating that it was a sign that the Day of Judgment was near.[136] He listed ten pages of comet-related disasters, including "earthquakes, floods, changes in river courses, hail storms, hot and dry weather, poor harvests, epidemics, war and treason and high prices". By 1700 most scholars concluded that such events occurred whether a comet was seen or not. Using Edmund Halley's records of comet sightings, however, William Whiston in 1711 wrote that the Great Comet of 1680 had a periodicity of 574 years and was responsible for the worldwide flood in the Book of Genesis, by pouring water on Earth. His announcement revived for another century fear of comets, now as direct threats to the world instead of signs of disasters.[135] Spectroscopic analysis in 1910 found the toxic gas cyanogen in the tail of Halley's Comet,[137] causing panicked buying of gas masks and quack "anti-comet pills" and "anti-comet umbrellas" by the public.[138]

If a comet is traveling fast enough, it may leave the Solar System. Such comets follow the open path of a hyperbola, and as such they are called hyperbolic comets. To date, comets are only known to be ejected by interacting with another object in the Solar System, such as Jupiter.[139] An example of this is thought to be Comet C/1980 E1, which was shifted from a predicted orbit of 7.1million years around the Sun, to a hyperbolic trajectory, after a 1980 close pass by the planet Jupiter.[140]

Jupiter-family comets and long-period comets appear to follow very different fading laws. The JFCs are active over a lifetime of about 10,000 years or ~1,000 orbits whereas long-period comets fade much faster. Only 10% of the long-period comets survive more than 50 passages to small perihelion and only 1% of them survive more than 2,000 passages.[32] Eventually most of the volatile material contained in a comet nucleus evaporates, and the comet becomes a small, dark, inert lump of rock or rubble that can resemble an asteroid.[141] Some asteroids in elliptical orbits are now identified as extinct comets.[142][143][144][145] Roughly six percent of the near-Earth asteroids are thought to be extinct comet nuclei.[32]

The nucleus of some comets may be fragile, a conclusion supported by the observation of comets splitting apart.[146] A significant cometary disruption was that of Comet ShoemakerLevy 9, which was discovered in 1993. A close encounter in July 1992 had broken it into pieces, and over a period of six days in July 1994, these pieces fell into Jupiter's atmospherethe first time astronomers had observed a collision between two objects in the Solar System.[147][148] Other splitting comets include 3D/Biela in 1846 and 73P/SchwassmannWachmann from 1995 to 2006.[149] Greek historian Ephorus reported that a comet split apart as far back as the winter of 372373 BC.[150] Comets are suspected of splitting due to thermal stress, internal gas pressure, or impact.[151]

Comets 42P/Neujmin and 53P/Van Biesbroeck appear to be fragments of a parent comet. Numerical integrations have shown that both comets had a rather close approach to Jupiter in January 1850, and that, before 1850, the two orbits were nearly identical.[152]

Some comets have been observed to break up during their perihelion passage, including great comets West and IkeyaSeki. Biela's Comet was one significant example, when it broke into two pieces during its passage through the perihelion in 1846. These two comets were seen separately in 1852, but never again afterward. Instead, spectacular meteor showers were seen in 1872 and 1885 when the comet should have been visible. A minor meteor shower, the Andromedids, occurs annually in November, and it is caused when Earth crosses the orbit of Biela's Comet.[153]

Some comets meet a more spectacular end either falling into the Sun[154] or smashing into a planet or other body. Collisions between comets and planets or moons were common in the early Solar System: some of the many craters on the Moon, for example, may have been caused by comets. A recent collision of a comet with a planet occurred in July 1994 when Comet ShoemakerLevy 9 broke up into pieces and collided with Jupiter.[155]

Ghost tail of C/2015 D1 (SOHO) after passage at the Sun

The names given to comets have followed several different conventions over the past two centuries. Prior to the early 20th century, most comets were simply referred to by the year when they appeared, sometimes with additional adjectives for particularly bright comets; thus, the "Great Comet of 1680", the "Great Comet of 1882", and the "Great January Comet of 1910".

After Edmund Halley demonstrated that the comets of 1531, 1607, and 1682 were the same body and successfully predicted its return in 1759 by calculating its orbit, that comet became known as Halley's Comet.[157] Similarly, the second and third known periodic comets, Encke's Comet[158] and Biela's Comet,[159] were named after the astronomers who calculated their orbits rather than their original discoverers. Later, periodic comets were usually named after their discoverers, but comets that had appeared only once continued to be referred to by the year of their appearance.[160]

In the early 20th century, the convention of naming comets after their discoverers became common, and this remains so today. A comet can be named after its discoverers, or an instrument or program that helped to find it.[160] For example, in 2019, astronomer Gennady Borisov observed a comet that appeared to have originated outside of the solar system, the comet was named C/2019 Q4 (Borisov) after him.

From ancient sources, such as Chinese oracle bones, it is known that comets have been noticed by humans for millennia.[161] Until the sixteenth century, comets were usually considered bad omens of deaths of kings or noble men, or coming catastrophes, or even interpreted as attacks by heavenly beings against terrestrial inhabitants.[162][163] In the 11th century Bayeux Tapestry, Halley's Comet is depicted portending the death of Harold and the triumph of the Normans at the Battle of Hastings.[164]

According to Norse Mythology, comets were actually a part of the Giant Ymir's skull. According to the tale, Odin and his brothers slew Ymir and set about constructing the world (Earth) from his corpse. They fashioned the oceans from his blood, the soil from his skin and muscles, vegetation from his hair, clouds from his brains, and the sky from his skull. Four dwarves, corresponding to the four cardinal points, held Ymir's skull aloft above the earth. Following this tale, comets in the sky, as believed by the Norse, were flakes of Ymir's skull falling from the sky and then disintegrating.[165]

In India, by the 6th century astronomers believed that comets were celestial bodies that re-appeared periodically. This was the view expressed in the 6th century by the astronomers Varhamihira and Bhadrabahu, and the 10th-century astronomer Bhaotpala listed the names and estimated periods of certain comets, but it is not known how these figures were calculated or how accurate they were.[166]

In 1301, the Italian painter Giotto was the first person to accurately and anatomically portray a comet. In his work Adoration of the Magi, Giotto's depiction of Halley's Comet in the place of the Star of Bethlehem would go unmatched in accuracy until the 19th century and be bested only with the invention of photography.[164]

Aristotle was the first known scientist to utilize various theories and observational facts to employ a consistent, structured cosmological theory of comets. He believed that comets were atmospheric phenomena, due to the fact that they could appear outside of the Zodiac and vary in brightness over the course of a few days. Aristotle's cometary theory arose from his observations and cosmological theory that everything in the cosmos is arranged in a distinct configuration.[167] Part of this configuration was a clear separation between the celestial and terrestrial, believing comets to be strictly associated with the latter. According to Aristotle comets must be within the sphere of the moon and clearly separated from the heavens. His theory on comets was widely accepted throughout the Middle Ages, despite several discoveries from various individuals challenging aspects of his work.[168] One notable challenger was Seneca, who questioned the logic of his predecessors sparking much debate among Aristotle's critics in the 16th and 17th centuries. Seneca thought comets to be more permanent than suggested by their brief flashes across the sky and provided thought provoking evidence of the celestial nature of comets .[168] He posed many questions regarding the validity of contemporary theories on comets, however, he did not author a substantial theory of his own.[169] Pliny the Elder believed that comets were connected with political unrest and death.[170] Pliny observed comets as "human like", often describing their tails with "long hair" or "long beard".[171] His system for classifying comets according to their color and shape was used for centuries.[172]

Astrological interpretations of comets proceeded to take precedence clear into the 15th century, despite the presence of modern scientific astronomy beginning to take root. In the 1400s, comets continue to forewarn disaster as seen in the Luzerner Schilling chronicles and in the warnings of Pope Callixtus III.[164] Regiomontanus was the first to attempt to calculate Diurnal parallax by observing the great comet of 1472. His predictions were not very accurate, but they were conducted in the hopes of estimating the distance of a comet from the Earth.[172]

In the 16th century, Tycho Brahe and Michael Maestlin demonstrated that comets must exist outside Earth's atmosphere by measuring the parallax of the Great Comet of 1577.[173] Within the precision of the measurements, this implied the comet must be at least four times more distant than from Earth to the Moon.[174][175] Based on observations in 1664, Giovanni Borelli recorded the longitudes and latitudes of comets that he observed, and suggested that cometary orbits may be parabolic.[176] Galileo Galilei one of the most renowned astronomers to date, even attempted writings on comets in The Assayer. He rejected Tycho Brahe's theories on the parallax of comets and claimed that they may be a mere optical illusion. Intrigued as early scientists were about the nature of comets, Galileo could not help but throw about his own theories despite little personal observation.[172] Kepler responded to these unjust criticisms in his work Hyperaspistes.

Also occurring in the Early modern period was the study of comets and their astrological significance in medical disciplines. Many healers of this time considered medicine and astronomy to be inter-disciplinary, and employed their knowledge of comets and other astrological signs for diagnosing and treating patients.[177]

Isaac Newton, in his Principia Mathematica of 1687, proved that an object moving under the influence of gravity must trace out an orbit shaped like one of the conic sections, and he demonstrated how to fit a comet's path through the sky to a parabolic orbit, using the comet of 1680 as an example.[178] Newton was one of the first to contribute to the physical understanding of the nature of comets.

In 1705, Edmond Halley (16561742) applied Newton's method to twenty-three cometary apparitions that had occurred between 1337 and 1698. He noted that three of these, the comets of 1531, 1607, and 1682, had very similar orbital elements, and he was further able to account for the slight differences in their orbits in terms of gravitational perturbation caused by Jupiter and Saturn. Confident that these three apparitions had been three appearances of the same comet, he predicted that it would appear again in 17589.[179] Halley's predicted return date was later refined by a team of three French mathematicians: Alexis Clairaut, Joseph Lalande, and Nicole-Reine Lepaute, who predicted the date of the comet's 1759 perihelion to within one month's accuracy.[180][181] When the comet returned as predicted, it became known as Halley's Comet (with the latter-day designation of 1P/Halley). It will next appear in 2061.[182]

In the 19th century, the Astronomical Observatory of Padova, was an epicenter in the observational study of comets. Led by Giovanni Santini (1787-1877) and followed by Giuseppe Lorenzoni (1843-1914), this observatory was devoted to classical astronomy, mainly to the new comets and planets orbit calculation, with the goal of compiling of a catalog of almost ten thousand stars. Situated in the Northern portion of Italy, observations from this observatory were key in establishing important geodetic, geographic, and astronomical calculations, such as the difference of longitude between Milan and Padua as well as Padua to Fiume.[183] In addition to these geographic observations, correspondence within the observatory, particularly between Santini and another astronomer Giuseppe Toaldo, about the importance of comet and planetary orbital observations.[184]

Isaac Newton described comets as compact and durable solid bodies moving in oblique orbit and their tails as thin streams of vapor emitted by their nuclei, ignited or heated by the Sun. Newton suspected that comets were the origin of the life-supporting component of air.[185]

From his huge vapouring train perhaps to shakeReviving moisture on the numerous orbs,Thro' which his long ellipsis winds; perhapsTo lend new fuel to declining suns,To light up worlds, and feed th' ethereal fire.

James Thomson The Seasons (1730; 1748)[186]

As early as the 18th century, some scientists had made correct hypotheses as to comets' physical composition. In 1755, Immanuel Kant hypothesized that comets are composed of some volatile substance, whose vaporization gives rise to their brilliant displays near perihelion.[187] In 1836, the German mathematician Friedrich Wilhelm Bessel, after observing streams of vapor during the appearance of Halley's Comet in 1835, proposed that the jet forces of evaporating material could be great enough to significantly alter a comet's orbit, and he argued that the non-gravitational movements of Encke's Comet resulted from this phenomenon.[188]

In 1950, Fred Lawrence Whipple proposed that rather than being rocky objects containing some ice, comets were icy objects containing some dust and rock.[189] This "dirty snowball" model soon became accepted and appeared to be supported by the observations of an armada of spacecraft (including the European Space Agency's Giotto probe and the Soviet Union's Vega 1 and Vega 2) that flew through the coma of Halley's Comet in 1986, photographed the nucleus, and observed jets of evaporating material.[190]

On 22 January 2014, ESA scientists reported the detection, for the first definitive time, of water vapor on the dwarf planet Ceres, the largest object in the asteroid belt.[191] The detection was made by using the far-infrared abilities of the Herschel Space Observatory.[192] The finding is unexpected because comets, not asteroids, are typically considered to "sprout jets and plumes". According to one of the scientists, "The lines are becoming more and more blurred between comets and asteroids."[192] On 11 August 2014, astronomers released studies, using the Atacama Large Millimeter/Submillimeter Array (ALMA) for the first time, that detailed the distribution of HCN, HNC, H2CO, and dust inside the comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON).[193][194]

Approximately once a decade, a comet becomes bright enough to be noticed by a casual observer, leading such comets to be designated as great comets.[150] Predicting whether a comet will become a great comet is notoriously difficult, as many factors may cause a comet's brightness to depart drastically from predictions.[203] Broadly speaking, if a comet has a large and active nucleus, will pass close to the Sun, and is not obscured by the Sun as seen from Earth when at its brightest, it has a chance of becoming a great comet. However, Comet Kohoutek in 1973 fulfilled all the criteria and was expected to become spectacular but failed to do so.[204] Comet West, which appeared three years later, had much lower expectations but became an extremely impressive comet.[205]

The Great Comet of 1577 is a well known example of a great comet. The Great Comet of 1577 passed near Earth as a non-periodic comet and was seen by many, including well-known astronomers Tycho Brahe and Taqi ad-Din. Observations of this comet led to several significant findings regarding cometary science, especially for Brahe.

The late 20th century saw a lengthy gap without the appearance of any great comets, followed by the arrival of two in quick successionComet Hyakutake in 1996, followed by HaleBopp, which reached maximum brightness in 1997 having been discovered two years earlier. The first great comet of the 21st century was C/2006 P1 (McNaught), which became visible to naked eye observers in January 2007. It was the brightest in over 40 years.[206]

A sungrazing comet is a comet that passes extremely close to the Sun at perihelion, generally within a few million kilometers.[207] Although small sungrazers can be completely evaporated during such a close approach to the Sun, larger sungrazers can survive many perihelion passages. However, the strong tidal forces they experience often lead to their fragmentation.[208]

About 90% of the sungrazers observed with SOHO are members of the Kreutz group, which all originate from one giant comet that broke up into many smaller comets during its first passage through the inner Solar System.[209] The remainder contains some sporadic sungrazers, but four other related groups of comets have been identified among them: the Kracht, Kracht 2a, Marsden, and Meyer groups. The Marsden and Kracht groups both appear to be related to Comet 96P/Machholz, which is also the parent of two meteor streams, the Quadrantids and the Arietids.[210]

Of the thousands of known comets, some exhibit unusual properties. Comet Encke (2P/Encke) orbits from outside the asteroid belt to just inside the orbit of the planet Mercury whereas the Comet 29P/SchwassmannWachmann currently travels in a nearly circular orbit entirely between the orbits of Jupiter and Saturn.[211] 2060 Chiron, whose unstable orbit is between Saturn and Uranus, was originally classified as an asteroid until a faint coma was noticed.[212] Similarly, Comet ShoemakerLevy 2 was originally designated asteroid 1990 UL3.[213] (See also Fate of comets, above)

Centaurs typically behave with characteristics of both asteroids and comets.[214] Centaurs can be classified as comets such as 60558 Echeclus, and 166P/NEAT. 166P/NEAT was discovered while it exhibited a coma, and so is classified as a comet despite its orbit, and 60558 Echeclus was discovered without a coma but later became active,[215] and was then classified as both a comet and an asteroid (174P/Echeclus). One plan for Cassini involved sending it to a centaur, but NASA decided to destroy it instead.[216]

A comet may be discovered photographically using a wide-field telescope or visually with binoculars. However, even without access to optical equipment, it is still possible for the amateur astronomer to discover a sungrazing comet online by downloading images accumulated by some satellite observatories such as SOHO.[217] SOHO's 2000th comet was discovered by Polish amateur astronomer Micha Kusiak on 26 December 2010[218] and both discoverers of HaleBopp used amateur equipment (although Hale was not an amateur).

A number of periodic comets discovered in earlier decades or previous centuries are now lost comets. Their orbits were never known well enough to predict future appearances or the comets have disintegrated. However, occasionally a "new" comet is discovered, and calculation of its orbit shows it to be an old "lost" comet. An example is Comet 11P/TempelSwiftLINEAR, discovered in 1869 but unobservable after 1908 because of perturbations by Jupiter. It was not found again until accidentally rediscovered by LINEAR in 2001.[219] There are at least 18 comets that fit this category.[220]

The depiction of comets in popular culture is firmly rooted in the long Western tradition of seeing comets as harbingers of doom and as omens of world-altering change.[221] Halley's Comet alone has caused a slew of sensationalist publications of all sorts at each of its reappearances. It was especially noted that the birth and death of some notable persons coincided with separate appearances of the comet, such as with writers Mark Twain (who correctly speculated that he'd "go out with the comet" in 1910)[221] and Eudora Welty, to whose life Mary Chapin Carpenter dedicated the song "Halley Came to Jackson".[221]

In times past, bright comets often inspired panic and hysteria in the general population, being thought of as bad omens. More recently, during the passage of Halley's Comet in 1910, Earth passed through the comet's tail, and erroneous newspaper reports inspired a fear that cyanogen in the tail might poison millions,[222] whereas the appearance of Comet HaleBopp in 1997 triggered the mass suicide of the Heaven's Gate cult.[223]

In science fiction, the impact of comets has been depicted as a threat overcome by technology and heroism (as in the 1998 films Deep Impact and Armageddon), or as a trigger of global apocalypse (Lucifer's Hammer, 1979) or zombies (Night of the Comet, 1984).[221] In Jules Verne's Off on a Comet a group of people are stranded on a comet orbiting the Sun, while a large manned space expedition visits Halley's Comet in Sir Arthur C. Clarke's novel 2061: Odyssey Three.[224]

NASA is developing a comet harpoon for returning samples to Earth

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Comet - Wikipedia

Comets | Facts, Information, History & Definition

Unlike the other small bodies in the solar system, comets have been known since antiquity. There are Chinese records ofComet Halleygoing back to at least 240 BC. The famousBayeux Tapestry, which commemorates the Norman Conquest of England in 1066, depicts an apparition of Comet Halley.

As of 1995, 878 comets have been cataloged and their orbits at least roughly calculated. Of these 184 areperiodiccomets (orbital periods less than 200 years); some of the remainder are no doubt periodic as well, but their orbits have not been determined with sufficient accuracy to tell for sure.

Comets are sometimes calleddirty snowballsor icy mudballs. They are a mixture of ices (both water and frozen gases) and dust that for some reason didnt get incorporated into planets when the solar system was formed. This makes them very interesting as samples of the early history of the solar system.

When they are near theSunand active, comets have several distinct parts:

Comets are invisible except when they are near the Sun. Most comets have highly eccentric orbits which take them far beyond the orbit ofPluto; these are seen once and then disappear for millennia. Only the short- and intermediate-period comets (like Comet Halley), stay within the orbit of Pluto for a significant fraction of their orbits.

After 500 or so passes near the Sun off most of a comets ice and gasis lost leaving a rocky object very much like anasteroidin appearance. (Perhaps half of the near-Earth asteroids may be dead comets.) A comet whose orbit takes it near the Sun is also likely to either impact one of the planets or the Sun or to be ejected out of the solar system by a close encounter (esp. with Jupiter).

By far the most famous comet isComet HalleybutSL 9was a big hit for a week in the summer of 1994.

Meteor shower sometimes occur when the Earth passes thru the orbit of a comet. Some occur with great regularity: thePerseidmeteor shower occurs every year between August 9 and 13 when the Earth passes thru the orbit of CometSwift-Tuttle. Comet Halley is the source of theOrionidshower in October.

Many comets are first discovered by amateur astronomers. Since comets are brightest when near the Sun, they are usually visible only at sunrise or sunset. Charts showing the positions in the sky of some comets can be created with aplanetarium program.

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Comets | Facts, Information, History & Definition

Comet Facts – Interesting Facts about Comets

Comet ISON stardustobservatory.org/images.php?page=details&id=363What is a Comet?

A comet is a very small solar system body made mostly of ices mixed with smaller amounts of dust and rock. Most comets are no larger than a few kilometres across. The main body of the comet is called the nucleus, and it can contain water, methane, nitrogen and other ices.

When a comet is heated by the Sun, its ices begin to sublimate (similar to the way dry ice fizzes when you leave it in sunlight). The mixture of ice crystals and dust blows away from the comet nucleus in the solar wind, creating a pair of tails. The dust tail is what we normally see when we view comets from Earth.

A plasma tail also forms when molecules of gas are excited by interaction with the solar wind. The plasma tail is not normally seen with the naked eye, but can be imaged. Comets normally orbit the Sun, and have their origins in the Oort Cloud and Kuiper Belt regions of the outer solar system.

There are many misconceptions about comets, which are simply pieces of solar system ices travelling in orbit around the Sun. Here are some fascinating and true facts about comets.

Comets come in several categories. The most common are periodic and non-periodic.

In the past, comets were named for their discoverers, such as Comet Halley for Sir Edmond Halley. In modern times, comet names are governed by rules set forth by the International Astronomical Union (IAU). A comet is given an official designation, and can also be identified by the last names of up to three independent discoverers.

Heres how it works. Once a comet has been confirmed, the following naming rules are followed. First, if the comet is a periodic comet, then it is indicated with a P/ followed by the year of its discovery, a letter indicating the half-month in which it was discovered, followed by a number indicating its order of discovery. So, for example, the second periodic comet found in the first half of January, 2015 would be called P/2015 A2.

A non-periodic comet would be indicated with a C/ followed by the year of its discovery, a letter indicating the half-month in which it was discovered, followed by a number indicating its order of discovery.

If a comet is independently discovered by three people named Smith, Jones, and Petersen, it could also be called Comet Smith-Jones-Petersen, in addition to its formal designation. Today, many comets are found through automated instrument searches, and so the formal designations are more commonly used.

Well-known comets include the non-periodic comets Hale-Bopp (C/1995 O1), Hyakutake (C/1996 B2), McNaught (C2006 P1), and Lovejoy (C/2011 W3). These flared brightly in our skies and then faded into obscurity.

In addition, Comet Shoemaker-Levy 9 (D/1993 F2) was spotted after it had broken up after a close call with Jupiter. (The D in its proper designation means it has disappeared or is determined to no longer exist). More than a year later, the pieces of the comet crashed into Jupiter.

The periodic Comet Halley (1P/Halley) is the most famous in history. It returns to the inner solar system once every 76 years. Other well-known periodic comets include 2P/Encke, which appears ever 3.3 years and 9P/Tempel (Tempel 2), which was visited by the Deep Impact and Stardust probes, and makes perihelion around the Sun every 5.5 years.

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Comet Facts - Interesting Facts about Comets

Overview | Comets NASA Solar System Exploration

Comets are cosmic snowballs of frozen gases, rock and dust that orbit the Sun. When frozen, they are the size of a small town. When a comet's orbit brings it close to the Sun, it heats up and spews dust and gases into a giant glowing head larger than most planets. The dust and gases form a tail that stretches away from the Sun for millions of miles. There are likely billions of comets orbiting our Sun in the Kuiper Belt and even more distant Oort Cloud.

The current number of known comets is:

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Kid-Friendly Comets

Kid-Friendly Comets

Comets orbit the Sun just like planets and asteroids do, except a comet usually has a very elongated orbit.

As the comet gets closer to the Sun, some of the ice starts to melt and boil off, along with particles of dust. These particles and gases make a cloud around the nucleus, called a coma.

The coma is lit by the Sun. The sunlight also pushes this material into the beautiful brightly lit tail of the comet.

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Comets get Ferland on conditioning loan – Utica Observer Dispatch

Ben Birnellbbirnell@uticaod.com

TuesdayFeb11,2020at2:07PM

The Utica Comets are getting another NHL veteran on a conditioning stint.

On Tuesday, the Vancouver Canucks announced rugged winger Micheal Ferland is joining the Comets on a long-term injury conditioning loan.Vancouver General Manager Jim Benning had mentioned Ferland would join Utica last week, but the trip ended up getting pushed back.

For Ferland -- who has been dealing with reported post-concussion symptoms twice this season and has been out since Dec. 10 -- the loan means he can play three games or spend up to six days with the Comets under rules.

The Comets schedule aligns well with that timeline as the team plays visiting Laval on Wednesday before playing Friday at Syracuse and Sunday afternoon at Rochester.

Ferland -- who will wear No. 79 with the Comets, according to the team's website -- did not practice with the team on Tuesday.

Defenseman Oscar Fantenberg and Antoine Roussel each had brief conditioning stints with the Comets earlier this season.

Ferland, who has played 355 NHL games, signed a four-year $14 million free-agent deal on July 10 with the Canucks to help provide a physical element as well as playmaking abilities to the lineup. He's also played with Calgary and Carolina.

In 14 games this seasaon with the Canucks, Ferland has a goal and four assists.

Ferland's games with the Comets won't be the first time he's played in Utica. As a member of teams then located in Abbotsford and Adirondack, Ferland played a total of six AHL games in Utica. The last one in Utica was while with Adirondack on Jan. 10, 2015. In total, he's played 64 AHL games with 71 penalty minutes.

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Comets get Ferland on conditioning loan - Utica Observer Dispatch

Devils slam on brakes to top Comets | Sports – The Independent

RUSSELL When the teams met in early December, West Carter and Russell took turns piling up points in the opening round of the Eastern Kentucky Conference tournament.

West Carter won an 85-81 shootout in overtime.

Tuesdays rematch looked nothing like that. Both defenses challenged every drive through the lane in a physical contest.

Russell struggled to get a basket early, but went on to feed off its own stops for a 61-47 victory in Marvin Meredith Gym.

Junior guard Charlie Jachimczuk called it one of the Red Devils top defensive performances.

Our coach (Tom Barrick) has been stressing defense all year, said Jachimczuk, who accounted for three of Russells eight steals. Its what we focus on the most. Tonight Ithink it was really good. Everybody did their part.

West Carter without guard catalyst Tyson Webb for the first time this season due to a concussion had a hard time getting open looks on the perimeter and met strong resistance around the basket. It resulted in 36-percent shooting and one of the Comets lowest scoring outputs of the season.

They are a team that likes to drive a lot, Jachimczuk said. Tyson Webb was out. (Braden) Leadingham is a pure driver. We tried to focus on closing off the lanes.

West Carter coach Jeremy Webb chalked it up as a tough night all around.

Its been what, eight days since we last had a game, he said. We couldnt practice for a while due to illness. We were down Tyson and just have some things to play through. Its just a part of what happens in the regular season.

Webb followed up by passing out kudos to the Red Devils.

Youve got to give Russell credit for the defense they played, Webb said. Theyre long and pretty athletic. Their length and overall defense gave us some difficulties.

West Carter (13-9) led 7-2 while Russell started 1-for-11 from the field. Then Tristan Millers 3-pointer triggered a 15-3 run in which the Red Devils scored three times off steals or Comets ballhandling miscues.

Russell closed the half with a similar flurry to take a 26-17 halftime lead. Miller opened the third quarter by coming off a screen to nail a 3-pointer. Teammate Brady Bell connected from long range following a West Carter turnover as the margin jumped to 15.

The Red Devils maintained at least a nine-point advantage the rest of the way. They made 23 of 28 second-half free throws, including 13 in a row during a stretch of the fourth quarter.

In all, Russell scored 26 points off West Carters 16 turnovers.

A lot of our offense goes through Tyson and Braden, said the Comets coach. Were having to learn without him. Were trying to replace 15 points and probably our best defender.

Leadingham finished with 16 points and Trevor Callahan added 11 for West Carter.

Russells Miller scored a game-high 22 hitting 6 of 8 floor shots and all eight of his free throw attempts. Jachimczuk joined him in double figures with 10 points.

Though the Red Devils 9-13 record isnt what their players and coaches wanted to this point, Jachimczuk likes the teams chances for making a postseason run.

I think we could go a pretty good ways in the tournament, he said. This (63rd) district is wide open with all four teams.

(606) 326-2671 |

rstanley@dailyindependent.com

W. CARTER FG FT REB TP

Jordan 1-3 2-2 1 4

B. Leadingham 6-16 3-4 6 16

Callahan 4-9 0-0 3 11

Dean 4-7 0-1 7 8

Tackett 0-4 0-0 3 0

Wilburn 1-4 0-0 1 2

Bond 2-6 1-2 0 6

Nichols 0-0 0-0 0 0

G. Leadingham 0-0 0-0 0 0

Team 5

TOTALS 18-49 6-9 26 47

FG Pct.: 36.7. FT Pct.: 66.7. 3-point FGs: 5-21 (Callahan 3-6, B. Leadingham 1-5, Bond 1-4, Jordan 0-1, Tackett 0-4, Dean 0-1). PF: 23. Fouled out: None. Turnovers: 16.

RUSSELL FG FT REB TP

Jachimczuk 2-7 6-10 3 10

Bell 1-9 6-6 2 9

Cantrell 1-3 4-4 7 6

Bechtel 1-4 0-0 2 2

Miller 6-8 8-8 3 22

Downs 2-3 2-2 5 6

Goodman 2-2 2-3 3 6

Quinn 0-0 0-0 0 0

Team 4

TOTALS 15-36 28-33 29 61

FG Pct.: 41.7. FT Pct.: 84.8. 3-point FGs: 3-8 (Miller 2-3, Bell 1-3, Jachimczuk, Downs 0-1). PF: 15. Fouled out: None. Turnovers: 13.

W. CARTER 10 7 14 16 47

RUSSELL 11 15 14 21 61

Officials: Jordan Barker, Larry Whelan, Tyler Maynard.

Original post:

Devils slam on brakes to top Comets | Sports - The Independent

Lady Comet torpedoes capture first sectional title in four years – chagrinvalleytoday.com

Motored by a sweep in diving and a trio of top-three finishes in the pool, the Solon girls captured the Division I sectional swim title on Saturday at the Spire Institute in Geneva.

Solon senior Tara Fitzgerald won the 1-meter springboard competition with an 11-dive score of 450.2 points to lead a one-two-three-four showing by the Lady Comets that also included freshman Alex Ludgate, 435.8 points, junior Abby Wilkov, 430.25 points, and freshman Bethany Mercer, 416.15 points.

That domination spotted the Solon girls a 56-point lead on defending champion Chardon, which was enough cushion to win their first sectional swim banner since 2016.

Behind top swim performances from freshman Grace Perlberg and sophomore Bridget Ferris, the Lady Comets scored 361 points to dethrone Chardon, 338 points, while Shaker Heights took third with 277 points and Mentor was fourth with 270 points in the 14-team field.

Perlberg finished third in the 200-yard freestyle in 2:00.46, while Ferris finished 10th in 2:05.66 and freshman teammate Ava Shaker was 12th in 2:07.08 to advance to district competition in that event.

Perlberg also took third in the 500 freestyle in 5:25.93, while Shaker was seventh in 5:38.23 and senior teammate Moraine Jackson was 11th in 5:51.44 to advance to districts.

Although Solon had a 56-point lead entering the swimming portion of the meet, the Chardon girls made up that deficit and actually owned a five-point lead on the Lady Comets entering the second-to-last event the 100 breaststroke.

But Solon put forth a three-four-five finish from Ferris, 1:14.20, junior Alexis DiMatteo, 1:15.13, and freshman Lilly Olpin, 1:15.29, to outscore the Lady Hilltoppers by 40 points in that event and create enough separation heading into the 400 freestyle relay.

The Chardon girls won the 400 freestyle relay in 3:41.37, while Solons quartet of Perlberg, 56.18 seconds, DiMatteo, 57.83, freshman Hannah Jones, 59.64, and Shaker, 58.41, clocked a 3:52.06 to finish fifth.

Individually, Jones took fifth in the 100 butterfly in 1:03.15, while sophomore teammate Irene Chang took ninth in 1:05.02 to qualify for districts.

In the 200 individual medley, Solon posted a five-six-seven finish from freshman Niya Fried, 2:23.48, Jones, 2:24.15, and Chang, 2:24.96.

Fried also punched her ticket to districts in the 100 backstroke by finishing ninth in 1:06.54.

And the Lady Comets 200 medley relay of backstroker Perlberg, 29.25 seconds, breaststroker Ferris, 33.37, butterflier Jones, 28.20, and freestyler DiMatteo, 26.39, clocked a 1:57.21 to finish third and advance.

See more here:

Lady Comet torpedoes capture first sectional title in four years - chagrinvalleytoday.com

Monsters special teams key in win over Comets – Utica Observer Dispatch

The Utica Comets have recently had mixed results on special teams.

That was again true for the Comets on Saturday against an efficient Cleveland Monsters power play.

The Monsters scored back-to-back goals on the man-advantage over about a two-minute span of game time and added another shorthanded goal to hand the Comets a 3-2 setback in a matinee to close a two-game set between the North Division opponents.

It was the third time in the last six games that the Comets have allowed two power-play goals. The Comets are 17-of-24 (70%) on the penalty kill over the six-game span. The team has dropped to 18th in the AHL on the penalty kill.

Cleveland (21-21-2-2, 46 points) finished 2-for-2 on the power play to help them win for the third time in four games. The Monsters sit near the bottom of the North Division.

The result spelled the fifth setback in the last six games for the Comets (26-18-2-2, 56 points), who are battling for position near the top of the North. The Comets whose 48 games played are most among North teams are 5-6-0-0 in their last 11 contests.

Utica got its own power-play goal from rookie forward David Pope to finish 1-for-5 on the advantage. Lukas Jasek also had a goal for the Comets, who lacked a physical aspect with the same lineup as Fridays shutout win as they remained without forwards Reid Boucher and Jonah Gadjovich among injured players. Justin Bailey and Zack MacEwen are on recall.

Zane McIntyre who had a couple quality saves on high-danger chances to keep the game close finished with 24 saves. Hes 11-10- 2 with a 3.16 goals-against average this season.

Special teams were a factor from the beginning for the Comets and Monsters.

The Comets opened the scoring 3:30 into the game with help from their sixth-ranked power-play. Utilizing strong puck movement by the teams second unit, Pope scored on a backdoor play following a quick pass from Carter Camper. Olli Juolevi also had a good setup to help start the tic-tac-toe play.

Clevelands penalty kill answered 3:12 later against the Comets aggressive power play. Calvin Thurkauf tied it at 1 when he snuck a shot from the right circle around Brogan Rafferty and over McIntyres glove.

It was the 12th shorthanded goal allowed by the Comets this season, which is most in the AHL.

With the Comets on the kill Francis Perron was off for hooking late in the period the Monsters Stefan Matteau made it 2-1 when his one-time blast from the right circle eluded McIntyre over his shoulder with 1:14 left.

Cleveland started the middle frame on the power play following a late Jasek penalty and extended the lead to 3-1 when Trey Fix-Wolansky buried a backdoor feed from Mark Dano just 1:10 into the period.

Utica pulled within 3-2 late in the second when Jasek put in a rebound from the slot for his 13th of the season. The Comets again showed good puck movement on the play with Nikolay Goldobin sending a pass to Jalen Chatfield, who had his one-timer from the high slot denied by Brad Thiessen.

It was Goldobins career-best 27th assist this season and his 100th career assist in the AHL.

The Comets made a good push in the third period, including pulling McIntyre late for an extra attacker. However, the Comets had a power-play late in the game halted after the officials called Kole Lind for tripping with 51 seconds to limit the Comets.

Ferland to join Comets

Canucks General Manager Jim Benning told Vancouver media that forward Micheal Ferland will join the Comets on a conditioning loan this week.

The rugged Ferland (upper body) has been on injured reserve since early December. According to rules, that would mean Ferlands stint would last six days. The loan could be extended, if needed.

Monsters 3, Comets 2

Utica 1 1 0 - 2

Cleveland 2 1 0 - 3

1st Period-1, Utica, Pope 1 (Camper, Juolevi), 3:30 (PP). 2, Cleveland, Thurkauf 6 (Bittner, Karlsson), 6:48 (SH). 3, Cleveland, Matteau 11 (Clendening, Stenlund), 18:46 (PP). Penalties-Fix-Wolansky Cle (hooking), 1:48; Vigneault Cle (slashing), 5:40; Perron Uti (hooking), 18:02; Jasek Uti (hooking), 19:18.

2nd Period-4, Cleveland, Fix-Wolansky 6 (Dano, Matteau), 1:10 (PP). 5, Utica, Jasek 13 (Chatfield, Goldobin), 16:04. Penalties-Somerby Cle (holding), 2:37; Clendening Cle (slashing), 19:41.

3rd Period- No Scoring.Penalties-Clendening Cle (delay of game), 18:37; Lind Uti (tripping), 19:09.

Shots on Goal-Utica 8-9-11-28. Cleveland 13-6-8-27.

Power Play Opportunities-Utica 1 / 5; Cleveland 2 / 2.

Goalies-Utica, McIntyre 11-10-2 (27 shots-24 saves). Cleveland, Thiessen 2-1-0 (28 shots-26 saves).

A-8,752

Referees-Beau Halkidis (48), Jake Jackson (76).

Linesmen-Tyson Baker (88), Jonathan Deschamps (84).

Read the original post:

Monsters special teams key in win over Comets - Utica Observer Dispatch

Physicists: Ancient life might have escaped Earth and journeyed to alien stars – Livescience.com

A pair of Harvard astrophysicists have proposed a wild theory of how life might have spread through the universe.

Imagine this:

Millions or billions of years ago, back when the solar system was more crowded, a giant comet grazed the outer reaches of our atmosphere. It was moving fast, several tens of miles above the Earth's surface too high to burn up as a fireball, but low enough that the atmosphere slowed it down a little bit. Extremely hardy microbes were floating up there in its path, and some of those bugs survived the collision with the ball of ice. These microbes ended up embedded deep within the comet's porous surface, protected from the radiation of deep space as the comet rocketed away from Earth and eventually out of the solar system entirely. Tens of thousands, maybe millions, of years passed before the comet ended up in another solar system with habitable planets. Eventually, the object crashed into one of those planets, deposited the microbes a few of them still living and set up a new outpost for earthly life in the universe.

Related: 5 Reasons to Care About Asteroids

You could call it "interstellar panspermia," the seeding of distant star systems with exported life.

We have no idea whether this ever actually happened .and there's a mountain of reasons to be skeptical. But in a new paper, Amir Siraj and Avi Loeb, both astrophysicists at Harvard University, argue that at least the first part of this story the depositing of the microbes into a comet that gets ejected from the solar system should have happened between one and a few dozen times in Earth's history. Siraj told Live Science that although a lot more work needs to be done to back up the finding, it should be taken seriously and that the paper may have been, if anything, too conservative in its estimate of the number of life-exporting events.

While the study's concept may seem far-fetched, humanity is constantly confronted with seeming impossibilities, like Earth going around the sun, or quantum physics, or bacteria hitching a ride into the galaxy aboard a comet that turn out to be true, Siraj said

And there's been reason to suspect that it might be possible. A series of experiments using small rockets in the 1970s found colonies of bacteria in the upper atmosphere. Comets really do enter and leave our solar system from time to time, and Siraj and Loeb's calculations show that it's plausible, maybe even likely, this has happened to large comets that graze Earth. Comets are porous, and might actually shield microbes from deadly radiation some microbes can survive a remarkably long time in space.

That alone is reason for scientists to take the idea seriously, Siraj said, and for researchers from fields like biology to jump in and figure out some of the details.

"It's a brand new field of science," he told Live Science

However, Stephen Kane, an astrophysicist at the University of California, Riverside, told Live Science that he was deeply skeptical of the suggestion that microbes from Earth might have actually turned up alive on alien planets through some version of this process.

The first problem would occur when the comet slammed into the atmosphere, he said. Siraj and Loeb point out that some bacteria can survive extraordinary accelerations. But the precise mechanism by which the microbes would adhere to the comet is unclear, Kane said, since the aerodynamic forces around the comet might make it impossible for any microbes to reach the surface and work their way deep enough below the surface to be protected from radiation.

It's also not clear, he said, whether any microbes would really have been up high in our atmosphere in the first place Those rocket experiments from the 1970s are old and questionable, he said, and we still don't have a good picture of what the biology of the upper atmosphere really looks like today let alone hundreds of millions of years ago, when comet encounters were much more common.

The biggest question, though, Kane said, is what would happen to the microbes after they landed aboard the comet. It's plausible, he said, that some bacteria might survive decades in space long enough to reach, say, Mars. But there's little direct evidence that any bacteria might survive the thousands or millions of years necessary to travel to another habitable star system. And that's really the key idea of this paper: Researchers have long suggested that debris from major collisions might blast life around between our solar system's planets and moons. But exporting life to an alien star system likely requires a more specialized scenario.

Still, Kane said, the calculations in this study of how precisely a comet might skim through the atmosphere were new to him, and "very interesting."

Siraj didn't strongly challenge any of Kane's concerns, but reframed them one by one as opportunities for further study. He wants to know, he said, precisely what the biology of the upper atmosphere looks like, and how comets might react to it. There's reason to think that at least some bacteria might survive super-long trips through deep space, he said, based on how robust they are under extreme conditions on Earth and in orbit. But for now, it's time for scientists across fields to jump in and start filling in the gaps, Saraj said.

Originally published on Live Science.

Excerpt from:

Physicists: Ancient life might have escaped Earth and journeyed to alien stars - Livescience.com

Utica Comets rocked Cleveland Monsters with a 3-0 shutout – The Cannon

Alex Bevan once sang You wanna make a hit record? Ill tell you what to do. You go to Cleveland. You can add to this statement by saying if you want to take in a hockey game, go to Cleveland. The 13,198 fans in attendance at tonights game would likely agree with this statement.

After five days off, the Cleveland Monsters were back in black (uniforms) to take on the Utica Comets. Its the first game back from five days off. Youre not sure what youre going to get, Head Coach Mike Eaves said of the extended break.

Both teams tried their hardest to hit Veini Vehvilainen and Michael DiPietro with their best shot. They kept firing away at the net. At one point, DiPietro launched his body across the crease to stop a laser beam from Kole Sherwood. The shot slammed right into DiPietros mask before bouncing behind the net.

After the five minute mark, things started to heat up between the two teams. Dylan Blujus came barreling towards Trey Fix-Wolansky with every intent to hit him and steal the puck. Fix-Wolansky had other plans on his mind. As Blujus neared his target, Fix-Wolansky quickly turned and laid a hit of his own.

The Comets responded to this hit by scoring a goal 5:08 into the game. Vehvilainen grabbed an errant puck from behind the net and flung it towards Gabriel Carlsson who was posted along the boards. Carter Bancks forced Carlsson to pass the puck behind the net to Adam Clendening. Within moments of receiving the puck, Clendening had his pocket picked by Tanner Sorenson who took off with the puck. From behind the net, Sorenson tossed the puck off to Bancks who tapped the puck into the net for the goal.

Not even a minute later, Derek Barach was collared for tripping putting the Monsters on their first penalty kill of the night. The Monsters struggled to get the puck into the neutral zone during the pk. However, Vehvilainen made a few good plays to prevent goals from happening.

With 7:13 left in the first period, Anton Karlsson dropped to the ground in an attempt to stop Nikolay Goldobins shot from entering the net. The puck flew past Karlssons ear like a summer breeze before it banged off the post into the net to give the Comets the 2-0 lead.

The second period started out with a few penalties from each team. Clendening accidentally kneed one of the Comets while trying to keep them from leaving the neutral zone with the puck. Brett Gallant noticed the Comets werent too pleased with the hit and immediately rushed to Clendenings side in case someones manners slipped . Jalen Chatfield started to come for Clendening in aid of his teammate. Gallant saw him lying low in the weeds ready to ambush Clendening and was all over him with the fervor of a barracuda. After the officials separated everyone, Chatfield and Gallant received a five minute major for roughing. While Clendening received two minutes for kneeing. The Monsters were able to successfully kill the penalty thanks to players like A. Karlsson who sped down the ice faster than a Maserati that goes 185 to chase down Comets who were on a breakaway with the puck.

With 11:13 left in the second period, the Monsters had a two-man advantage for two minutes. They were unable to do anything with the 5-on-3 due to the fact the Comets created a triangle formation in the slot. This formation prevented the Monsters from being able to fire off any decent passes or shots on net.

Early in the third period, Sam Vigneault turned on the burners and fired off a shot at DiPietro. The shot was quickly stopped but Paul Bittner pushed the rebound into the net for the goal. Or so everyone thought. The official quickly waived it off as a no goal. They said it was goalie interference. That was the length of it. Its not reviewable in our league, explained Coach Eaves, We were caught shorthanded on that one. Its the referees discretion. Thats what we were told.

To say the fans were not pleased with the no-goal call would be an understatement. Hate is a strong word but the fans really, really, really didnt like the refs for that call. Boos rained down from every corner of Rocket Mortgage FieldHouse. Then, the ref you suck chants could be heard out of the mouth of both the young and old. As the game continued, the boos for the officials continued. Typically when there is an official timeout fans yell What official?. Tonight, the word official was met with boos upon boos.

The Monsters were never able to get their momentum back. In the waning minutes of the game, the Monsters went on the two-man disadvantage where the Comets delivered the final blow in the form of a power play goal.

Despite the loss, the Monsters fans still have the teams back. The Monsters have their ups and downs. It doesnt matter because this is their team and theyll be right back here at 1pm on Saturday to cheer the Monsters to a redemption victory.

1st - Michael DiPietro (Utica Comets) - 27 saves, 27 shots faced, 60:00 TOI2nd - Carter Bancks (Utica Comets) - 1g, 0a3rd - Nikolay Goldobin (Utica Comets) - 2g, 0a

Stefan Matteau - Kevin Stenlund - Trey Fix-WolanskyMarko Dano - Ryan MacInnis - Kole SherwoodCalvin Thurkauf - Sam Vigneault - Paul BittnerBrett Gallant - Derek Barach - Maxime Fortier

Gabriel Carlsson - Adam ClendeningDillon Simpson - Andrew PeekeAnton Karlsson - Doyle Somerby

See the article here:

Utica Comets rocked Cleveland Monsters with a 3-0 shutout - The Cannon

Comet of the Week: Tago-Sato-Kosaka 1969g – RocketSTEM

My very first comet observation. This is the sketch I made of Comet Tago-Sato-Kosaka as it appeared through my 11-cm reflector on the evening of February 2, 1970.Comet Tago-Sato-Kosaka 1969gsPerihelion: 1969 December 21.27, q = 0.473 AU

Everyone fondly remembers their first. When it comes to comets, my first came exactly 50 years ago on Monday evening, February 2, 1970, when I was 11 years old and in the 6th Grade, and involved a 5th-magnitude fuzzball located close to the 2nd-magnitude star Hamal in the constellation Aries. My best friend, Mark Bakke who was every bit as much into astronomy as I was came over and brought his 60-mm refractor, and by using information within the magazine Sky & Telescope and a pair of 735 binoculars I easily located the comet. I could faintly see it with my unaided eye, and through the 11-cm reflector I had recently acquired it appeared as a bright, diffuse coma with a distinct central condensation. In addition to Mark, I successfully convinced the various members of my family, which included my father, my mother, my paternal grandmother, and my older brother Barry (then 16 years old) to come out and look at it, although to be honest I think I they were a bit underwhelmed. Mark and I, on the other hand, were about as excited as one can be, and we shared our observation with our teacher and classmates at school the following day.

The comet in question had been discovered on October 10, 1969, by a Japanese amateur astronomer, Akihiko Tago. He waited two nights to confirm it, and when he did so it was independently picked up by two more (quite young) Japanese amateur astronomers, Yasuo Sato (age 19) and Kozo Kosaka (age 17). At the time of its discovery Comet Tago-Sato-Kosaka was about 10th magnitude and visible in the western sky after dusk; it traveled southward and brightened, becoming inaccessible from the northern hemisphere in early November and disappearing into twilight from the southern hemisphere in early December, by which time it was about 6th magnitude.

The comet became observable from the southern hemisphere again during the latter part of December, and was reported as being as bright as magnitude 2 to 3, and with a distinct tail. In early January 1970 it started heading back north, and for a while its brightness held fairly steady as it was still approaching Earth (closest approach being 0.38 AU on January 20). It was still around 4th magnitude when it became accessible again from the northern hemisphere in mid-January.

Comet Tago-Sato-Kosaka became the first comet ever to be observed from space, when beginning on January 14 and continuing for the next two weeks a team of astronomers led by Arthur Code at the University of Wisconsin observed it with the Orbiting Astronomical Observatory 2 (OAO-2) spacecraft that had been launched in late 1968. OAO-2s ultraviolet detectors recorded a large cloud of hydrogen almost three degrees across 1 times the diameter of the sun in physical terms. The existence of such a cloud was not unexpected, in fact it had been predicted by the German astronomer Ludwig Biermann in 1964. These Lyman-alpha clouds have now been detected surrounding many other comets, and indeed they are now known to accompany most comets visiting the inner solar system. These and other spacecraft observations of comets are discussed in this weeks Special Topics presentation.

As I indicated, the comet had faded to 5th magnitude by early February. I followed it every night for the next week, and on the evening of February 6 it seemed surprisingly bright, and was easily detectable with the unaided eye. I would later learn that the comet had undergone a brief outburst at that time, and there is some evidence that it might have undergone a small fragmenting event then. On the next two nights the comet had faded back to its normal brightness, and after being clouded out on the evening of the 9th I didnt look for it again. According to other observers, it faded steadily, to around 11th magnitude in early April, and the final photographs were obtained in early May.

50 years later, it occurs to me that, of the five people who shared that initial comet observation with me, only one is still alive. My grandmother passed away in 1973, my father in 2002, and my mother in 2013; Mark, meanwhile, was tragically killed in a gunshot accident in 1984 at the age of 27. My brother Barry is still going strong at age 66 and I hope he continues doing so.

Orbital calculations indicate that Comet Tago-Sato-Kosaka is traveling in a very elongated orbit that will bring it back in about 110,000 years. Perhaps any beginning comet observers from whoever, or whatever, will be living on Earth at that time will once again be able to view it.

Ice and Stone 2020 Week 6 consists of three other articles:This Week in History: February 2-8Special Topic: Comet observations from spaceFun & Games: Word Search #1

Return to home page for Ice and Stone 2020

All of the Ice and Stone 2020 educational materials for Week 6 are available in a PDF format.CLICK HEREto download the content from any of the released weeks.

Original post:

Comet of the Week: Tago-Sato-Kosaka 1969g - RocketSTEM

Duncan, Pitre named Barker Honda Athletes of the Week – Daily Comet

Chris Singleton Staff Writer @courierchris

FridayJan31,2020at3:13PM

Central Lafourche boys basketball player Ashtrein Duncan and South Lafourche girls basketball player Ava Pitre were named the winners of the Barker Honda Athletes of the Week contest presented by The Courier and Daily Comet today.

Both athletes won a fan vote that took place from Jan. 25-30 at houmatoday.com and dailycomet.com.

Duncan won the male honor after he led the Trojans with 21 points during a 62-56 win over Destrehan on Jan. 24. He had 18 points during a 66-53 win over East St. John on Jan. 21.

South Lafourche basketball player Eric Thibodaux was second in the male contest voting, and Thibodaux basketball player Darwin Davis was third.

Pitre won the female honor after she scored 23 points in a 61-56 win over Vandebilt on Jan. 21.

Central Lafourche soccer player McKenzie Champagne was second in the female contest voting, and Vandebilt Catholic soccer player Sydne Marcel was third.

Every week, local fans will get to visit The Courier and Daily Comets websites at houmatoday.com and dailycomet.com and cast their vote in the player of the week poll. Area athletes from all 13 local high schools in The Courier/Daily Comets coverage area are eligible for the player of the week honors.

The players will be nominated based on their athletic achievements in every sport each week throughout the high school sports calendar year, and the winners will receive a framed certificate and have their picture printed in the paper.

Visit our websites at noon Saturday to see the new list of player of the week candidates.

Read more:

Duncan, Pitre named Barker Honda Athletes of the Week - Daily Comet


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