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Comet – Wikipedia

Icy small Solar System body

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 it's 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 after the Battle of Ragnarok 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 Ymirs 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

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:

Go farther. Explore Comets in Depth

Key Science Targets

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.

Visit NASA Space Place for more kid-friendly facts.

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Overview | Comets NASA Solar System Exploration

Wave finish strong to beat depleted Kansas City Comets – The Blue Testament

After three quarters of edge-of-your-seat arena soccer, the Milwaukee Wave ran out victorious with a big final 15 minutes to hand the Comets their fifth loss of the season by a score of 8-3 in front of 5,126 fans, which is the second largest home crowd in team history (2010-Present). This puts the Comets average attendance at 4,235, which is second in the entire league after finishing last season in 12th place with an average attendance of 1,988.

The Comets entered Saturdays match without John Sosa, Adam James, and Ray Saari, and Mark Saxby, who watched on the bench as Lou Misner got his third career start.

Milwaukee scored the only goal of the first quarter, as Luan Oliviera scored on the powerplay. Leo Gibson leveled the score for the Comets at 1-1, capitalizing on a bad error by Wave keeper Rafa Dias. Milwaukee quickly retook the lead after Alex Bradley fired in his fourth goal of the season. After a pretty calm opening 25 minutes, the referees were the subject of attention in the closing minutes after a couple questionable calls and an incident between Ray Lee, Max Ferdinand, and Angel Curiel that caused a little brawl.

Ian Bennett added a third for the Wave, assisted by Marcio Leite on the powerplay to make it 3-1 Wave. Robert Palmer assisted Stefan Stokic to bring the Comets back within a goal, as Stokic scored his first goal since December of 2018. Alex Bradley scored another couple to complete his hat trick to give Milwaukee the 5-2 advantage in the fourth period. Ian Bennett added his second of the evening to make it 6-2 against the Comets sixth attacker. Gibson scored his second of the night late in the fourth to make it 6-3. Bennett finished his eighth career hat trick against the Comets and another goal from Isaac Pereyra put the final scoreline at 8-3 as the Wave handed the Comets their first home loss of the season and remained undefeated on the road this season.

The Comets drop to 3-5 and have lost two straight while Giuliano Oliviero and the Wave improve to 6-1 and have now gone five without facing defeat.

After a very good first three quarters, especially without Sosa, James, Saari, Saxby, and an injury to Lucas Rodriguez in the first quarter as Stefan Stokic picked up another injury in the second half, the Comets tired legs collapsed as they chased to draw level. The Wave showed why they are the defending champions, as they capitalized on Comets mistakes both mentally (giving Milwaukee two preventable first half powerplay goals) and physical mistakes.

Although Lou Misner stepped up again with some good saves, his distribution was poor. The Comets third keeper of the season had too many misplaced passes either to the other team or fired out of bounds, which made it difficult at times for the Comets to build from the back and retain possession. In Kevin Ellis first game back with the Comets, he picked up a decent amount of minutes, but wasnt hugely effective.

No loss is a good loss, but it is a loss that head coach Leo Gibson should be able to live with. The Comets hung with the champions for the first three quarters, which is always a good sign. This was certainly a loss in which good things can be taken from, but also plenty to learn from, especially when it comes to getting frustrated. The Wave maintained calm heads the entire match, which ended up being the difference between the two sides.

The Comets return to action next Friday, January 17th, when they welcome the Orlando SeaWolves to Silverstein Eye Centers Arena for the first time this season.

Elsewhere around the MASL, former Comet Alex Megson scored a sensational bicycle kick as the Tacoma Stars defeated the Mesquite Outlaws by a score of 8-5.

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Wave finish strong to beat depleted Kansas City Comets - The Blue Testament

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, 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

Vikings Split With Comets | Sports – Southern Pines Pilot

Union Pines split with Asheboro Friday in non-conference basketball action.

The Viking boys grabbed a 54-49 overtime win while the Viking girls fell 70-61 to the Blue Comets.

In the boys game, the Vikings outscored the Blue Comets 8-3 in overtime to improve to 6-8 this season.

The Vikings used a balanced scoring attack, getting points from seven players, including three in double figures, in getting the win.

Isaiah Robbins led the way with 14 points while teammates Tyreek McCoy and Jalen Eberhart added 10 points each.

Other Viking scorers included Archie Chandler with seven and Ahmad Jones and Jacob Bowbliss with five each. Stevenson Haskell added three for the Vikes.

In the girls game, the Blue Comets used a big third quarter and the dynamic duo of Tanaesha Ellison and Diamond McDowell, who combined for 60 of Asheboros 70 points.

Ellison finished with 32 and McDowell with 28 for the Blue Comets, who are now 9-4 overall.

Union Pines led 39-37 at the half, but the Blue Comets outscored the Vikings 23-9 in the third quarter to take control of the contest.

Emily Bowbliss led the Vikings, now 8-6 overall, with 20 points. Emma Ring and Kaley Evans had 10 each, Sara Adams nine and Molly Schmitz had eight.

Union Pines starts Tri-County 6 Conference play Friday when the Vikings travel to Harnett Central for a doubleheader.

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Vikings Split With Comets | Sports - Southern Pines Pilot

Balanced Comets sparkle in win over Rangers – Rapid City Journal

Rapid City Christian senior guard Payton Causey drives for two points in the first quarter of Friday night's win over Hill City.

Rapid City Christian junior Sam Schlabach is fouled as he drives to the basket Friday night against Hill City.

Rapid City Christian boys' basketball coach Kyle Courtney couldnt have asked for much more from his Comets during their 80-27 win over Hill City Friday night at Hart Ranch.

Courtneys squad played tough, pressing defense, forcing 15 first-half turnovers to take early control of the game. Christian was efficient with its shots and unselfish on the offensive end of the floor, with 10 Comets reaching the scoring column against a young Rangers squad.

By the time the game wrapped up, Christian had a fourth quality all-court game under its belt heading into a tough stretch of contests over the next two-plus weeks that starts Jan. 9 at Wall and ends Jan. 21 with a home game with Red Cloud. In between, the Comets will face Madison in a make-up game lost in December due to inclement weather.

Were a pretty veteran group, Courtney said. My starting five have been playing varsity ball for a while now, and weve got some good young players. Weve got some ability. The challenge is always playing up to your potential.

The Comets made it look easy Friday.

A stifling press and the ability to play both zone and man defenses interchangeably kept the Rangers from getting into their offensive sets most trips down the floor. Eight turnovers in the first quarter led to a 24-7 lead by the end of eight minutes of play. Christian turned over Hill City seven more times in the second quarter and led 45-10 at halftime.

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Balanced Comets sparkle in win over Rangers - Rapid City Journal

Comet of the Week: Machholz C/2004 Q2 – RocketSTEM

Ultraviolet image of Comet Machholz taken by NASAs GALaxy Evolution EXplorer (GALEX) spacecraft on March 1, 2005. The purple represents the hydroxyl molecule (OH) and the yellow represents the molecule CS. Image courtesy NASA/JPL-Caltech/University of Washington/Jeffrey Morgenthaler.Comet Machholz C/2004 Q2s Perihelion: 2005 January 24.91, q = 1.205 AU

Beginning with French astronomer Charles Messier and his contemporaries in the mid- to late 18th Century, the vast majority of comets were discovered visually by amateur astronomers who regularly swept the skies looking for these objects. While this means of comet discovery began to be supplanted by photographic patrol programs in the early 20th Century, the visual hunters continued to Anhold their own for the next several decades. It was only when the CCD-based survey programs, which cover the sky extensively every month and are able to detect incoming comets when they are still too faint to be detected visually, became operational near the end of the 20th Century that visual comet discoveries essentially became a lost art. Only a handful of such discoveries have been made since the beginning of the 21st Century.

One of the most successful comet hunters of recent times is American amateur astronomer Don Machholz, a long-time resident of California who resided near San Jose and then relocated to Colfax (near Sacramento) in the early 1990s. Don, whom I have known personally for many years and consider a good friend, began his comet-hunting efforts at the beginning of 1975. If there is any one characteristic that embodies a successful comet hunter, it is perseverance, and Don truly exemplifies this: while the conventional wisdom is that a comet is discovered, on average, after 200 to 300 hours of searching, Don put in 1700 hours before making his first discovery in September 1978.

As of now Don has discovered a total of 12 comets. Most of these have been rather nondescript objects, however, two of them are short-period comets that have turned out to be quite interesting: 96P/Macholz 1 (discovered in May 1986) has a very small perihelion distance (0.13 AU) and appears to be related to several inner-solar system phenomena including meteor showers and groups of small comets that have been detected by the SOlar and Heliospheric Observatory (SOHO) spacecraft; and 141P/Machholz 2 (discovered in August 1994) has been accompanied on some of its returns by various companion comets that have apparently come about as a result of fragmenting of its nucleus. This latter comet returns to perihelion, under relatively favorable viewing conditions, late this year.

Don discovered his 10th comet, and what would be his best one, on the morning of August 27, 2004, a discovery that took place almost ten years after his previous one and which, remarkably, took place in the teeth of the comprehensive surveys that were already operating. The comet was around 11th magnitude when discovered, but brightened steadily over the coming weeks as it approached the sun and Earth, and by the latter part of November had become visible to the unaided eye from dark rural sites.

Comet Machholz was at its best in early January 2005, when it passed 0.35 AU from Earth on the 5th and passed two degrees west of the Pleiades star cluster (M45) going from south to north just a couple of days later. At that time the comet was slightly brighter than 4th magnitude and exhibited a coma half a degree in diameter; it also exhibited a faint ion tail up to two degrees long (visually) and a fainter, shorter dust tail.

After its passage by the Pleiades the comet remained detectable with the unaided eye until early March, at which time it was also passing five degrees from the North Celestial Pole. It continued fading after that, and I was able to follow it visually until the end of August, just beyond the one-year anniversary of its discovery.

Since that time Don has continued his visual comet hunting, and despite the competition from the comprehensive surveys he has managed to discover two more, a faint one in March 2010 and a somewhat brighter one as recently as November 2018. This latter one, which was independently discovered by two Japanese amateur astronomers using CCDs, is known as Comet Machholz-Fujikawa-Iwamoto C/2018 V1 and became slightly brighter than 9th magnitude as it approached perihelion in early December of that year. It was the first visual comet discovery in over eight years and shows that, perhaps, visual comet discovery may not entirely be a dead practice yet. Don, who is now 67 years old and who recently relocated to rural northwestern Arizona, continues to hunt for new comets, and, who knows? There conceivably could still be more Comets Machholz to come . . .

Ice and Stone 2020 Week Two consists of two other articles:

This Week in History: January 5-11

Special Topic: Near-Earth asteroids

Return to home page for Ice and Stone 2020

All of the Ice and Stone 2020 educational materials for Week Two are available in a PDF format.CLICK HERE to download the file.

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Comet of the Week: Machholz C/2004 Q2 - RocketSTEM

Comets put clamps on cold-shooting Panthers to win title – SaukValley.com

ERIE Newman coach Ray Sharp broke out his lucky blue suit for the championship game of the Warkins Memorial Classic on Monday night.

In the end, it was his Comets who gave Erie-Prophetstown the blues.

Newman broke open a tight game with a third-quarter burst and cruised home with a 42-29 win over the Panthers. The Comets defended the title they also won in 2018.

Its always our goal to come out and win tournaments, sophomore forward Marcus Williams said. This tournament was huge for our bench guys, giving us good defensive and offensive minutes, and to win is icing on the cake.

Erie-Prophetstown (5-6) was within 20-19 after a free throw from Bryce Rosenow with 6 minutes, 6 seconds left in the third quarter when Newman (13-2) made its move. Backup forward Brett Newman drained a 3-pointer, then Williams followed with a pair of steals and layups to up his teams lead to 27-19 less than a minute later.

In the locker room at halftime, we talked about coming out with a lot of intensity in the third quarter, Williams said. We were a little bit slow the first 2 minutes, but something just clicked. It was one of the steals we had at the top of the 1-3-1, and we used that energy the rest of the game.

Williams dropped in a layup at the third-quarter buzzer to give Newman a 36-21 lead. The Panthers opened the fourth quarter on a 6-0 run to get within nine points, but managed just a pair of free throws and no baskets the rest of the way.

Erie-Prophetstown was 11-for-39 from the field against some typically sticky Newman defense, but it was equal parts Comets D and poor shooting.

I give Erie-Prophetstown a lot of credit, Sharp said. They were running their offense really well against our 1-3-1 and man, and getting good shots. Fortunately for us, they missed some tonight, and we were able to get some rebounds.

E-P coach Ryan Winckler echoed those sentiments.

I thought we executed well, with the the exception of a couple of times where we got trapped, but thats going to happen against Newman, Winckler said. They play so hard and cover the court so well. I was super-happy. I thought we got some tremendous looks, and a lot of teams dont get those looks against Newman. Weve just got to knock em down.

Clayton Johnson made 5 of 6 shots from the field to lead the Panthers with 10 points, but his teammates were a combined 6-for-33. Rosenow and Eric Robinson each had six points. Robinson also had seven rebounds and four blocked shots, while Johnson corralled a team-high nine boards.

Williams, the tournament MVP, led Newman with 18 points, while Devon House added nine points and 13 rebounds.

Boys basketball

Warkins Classic championship

Newman 42, Erie-Prophetstown 29

Star of the game: Marcus Williams, Newman, 18 points, 7 rebounds, 5 steals

Key performers: Devon House, Newman, 9 points, 13 rebounds; Clayton Johnson, E-P, 10 points

Up next: Princeton at Erie-Prophetstown; Kewanee at Newman, both 7 p.m. Friday

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Comets put clamps on cold-shooting Panthers to win title - SaukValley.com

Comets to get early start on softball base paths – Mooresville Tribune

Doing so just in time to complete the extended celebration surrounding the arrival of the New Year, the Mooresville-based Comets youth fastpitch softball organization will toss out opening pitches in preparation for the upcoming tournament season.

The Comets will be conducting open tryouts for any and all interested prospects over the upcoming weekend, the first full one of 2020.

Taking place on Sunday afternoon, the Comets will be staging initial tryout sessions for a pair of its age-oriented outfits.

Tryouts for the Comets 8-and-under as well as 12-U teams will take place at the same time, same date and same site.

The tryouts will be held on the softball field in place on the Pine Lake Prep facility off N.C. Highway 21.

Both affairs will be held from 1-3 p.m.

Team roster availabilities are open on both teams for participation in scheduled play that will be held during the 2020 season.

Alaina Harmon will be in charge of the 8-U workouts. She can also be reached at 704-516-2893 for additional details.

Dale Gilmore will take the reins of the 12-U tryouts. He can be contacted at 704-778-2042 for additional details.

Additional similar tryouts may also be held as well in order to help finalize the rosters for the tournament-caliber teams.

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Comets to get early start on softball base paths - Mooresville Tribune

HCHS shatters Martinsville’s zone defense in 73-51 win; improve to 8-0 on the season – YourGV.com

Kameron Roberts said he and his Halifax County High School teammates had not had the best of practices following the Comets' championship run in the Gazette-Virginian Holiday Classic Basketball Tournament at Halifax County High School.

"We had had a bad practice week," Roberts said.

"We knew we had to play better."

The Comets definitely did that.

Breaking apart Martinsville High School's zone defense and staging a strong defensive effort of its own, Halifax County High School grabbed a 15-point lead in the first quarter and went on to defeat the Bulldogs 73-51 in Friday night's Piedmont District game at Halifax County High School.

Friday night's win improved the Comets' record to 8-0 overall and 2-0 in Piedmont District play. The district wins are against GW and Martinsville High School, the teams most observers felt would be the chief challengers for the regular-season district title along with the Comets. Martinsville High School dropped to 4-4 overall with the loss.

Comets head coach Sterling Williams said he was pleased with how his team responded after not having had a good series of post-tournament practice sessions.

"I felt our focus (in practice) could have been better," said Williams, "but we came out in the first half and played really well, scoring 24 points in that first quarter. This team is kind of young, and when you have that many days off during the (holiday) break, and you're the only team that is practicing, it's a little bit different, especially when you have a district game on one of those days against Martinsville, which is a really good ballclub."

The Comets had four players to reach double figures in scoring, with Roberts leading the team with a game-high 23 points. Jaden Waller followed with 17 points, Zach Carter tallied 11 points and Davon Jennings chipped in 10 points.

Kevon Ferrell was next in line with seven points, Keshawn Wells scored three points and Amoa Jones had two points.

One of the keys to the Comets' win was their ability to break down Martinsville High School's zone defense in the first half with a combination of points in the paint and in transition, as well as hitting a trio of 3-pointers.

"This week gave us a chance to prepare for the zone defense," Williams pointed out.

"We had seen it a couple of times. Person High School had played it against us, and Prince Edward County High School had played it a little bit. We had been handling it pretty well. Tonight was really good. We had a really good first quarter, and a really good start to the fourth quarter. They (Martinsville High School) had to go man-to-man, and we were able to run our "man" offense."

Aided by a technical foul against the Bulldogs that occurred prior to the start of the game, the Comets jumped out to a 5-0 lead in just over a minute. Later, leading 7-4, the Comets went on a 12-0 run that included three baskets from Jennings to go up 19-4 with 3:23 left in the opening quarter. A 3-pointer from Waller with 10.4 seconds left in the quarter gave the Comets a 24-12 edge.

The Comets went on to lead by as many as 17 points in the second quarter before taking a 36-25 lead into the halftime break.

Martinsville High School closed the gap to eight points when Troy Brandon hit a pair of free throws with 4:17 left in the third quarter, and pulled to within seven points when Brandon canned a 3-pointer with 2:04 left in the third period.

A three-point play from Carter with 1:27 left in the period put the Comets back up by 10 points at 49-39. Two free throws from Roberts and a basket from Carter in the final 59 seconds of the period gave the Comets a 53-41 lead heading into the fourth quarter.

The Comets took full control of the game with a 10-0 run in the first 1:29 of the fourth quarter. A pair of 3-pointers from Roberts, a layup from Waller after a steal, and a layup from Ferrell in transition gave the Comets a 63-41 lead. Martinsville High School never recovered.

Defensively, the Comets were solid, with 16 points being the most points Martinsville High School scored in any quarter.

"Defense was where the game was won," Williams remarked.

"Keeping those guys (Martinsville High School) out of the lane was big. Troy (Brandon) and 35 (Jaheim Niblett) are really good players. They can create their own shot at any time. Niblett did that in the first half. He really got off, and then Troy kind of took over the second half. We did a good job of not letting the other guys score and hurt us, forcing them to take tough shots. We also did a decent job of rebounding the basketball."

Brandon led the Bulldogs in scoring with 22 points, 14 of which he scored in the second half. Niblett followed with 14 points, six of which he scored in the second quarter. Jalil Martin was next in line with 11 points.

Halifax County High School's Jaden Waller (4) is all alone as he sails to the basket for an easy dunk during the second half of Friday night's Piedmont District game against Martinsville High School at Halifax County High School. Waller scored 17 points in the game.

Halifax County High School's Zach Carter (44) leaps between a pair of Martinsville High School players to grab a rebound during the second half of Friday night's Piedmont District game at Halifax County High School.

Halifax County High School's Jhamad Lawson (5) attempts to flip the ball up to the basket out of the reach of Martinsville High School's Jaheim Niblett (35) during the first half of Friday night's Piedmont District game at Halifax County High School.

Halifax County High School's Kameron Roberts (14) fires up a shot over Martinsville High School's Jaheim Niblett (35) to score two of his game-high 23 points in Friday night's Piedmont District game at Halifax County High School.

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HCHS shatters Martinsville's zone defense in 73-51 win; improve to 8-0 on the season - YourGV.com

Kansas City Comets end 2019 with New Years Eve clash in St. Louis – The Blue Testament

Kansas City Comets at St. Louis Ambush

When: Tuesday, December 31st, 2019 at 3:05 PM CT

Where: The Family Arena, St. Charles, Missouri

How to Watch/Stream: Masl.tv/YouTube

The Kansas City Comets will end the year with a visit to their closest rival, the St. Louis Ambush, on New Years Eve.

Having already met twice this season, the Comets won their home opener in November and the Ambush had an overtime win earlier this month. Tuesdays game will be the second of three visits to The Family Arena this season Leo Gibsons side.

The Ambush enter the game with a 2-3 record, coming off their second victory of the season over the Tacoma Stars. Led by head coach Hewerton Moreira, the Ambush have had players step up after losing several key players last season as Tony Walls leads the team with nine points in five games with six goals and three assists. Former Comet Stefan St. Louis is still searching for his first goal of the season, while another former Comet Andre Braithwaite opened his scoring account with the Ambush in Fridays victory over the Stars.

The Comets also come off a victory over the Tacoma Stars. Leo Gibson has already racked up 14 points from seven goals and seven assists, but Ray Lee is fresh from his first ever hat trick for the Comets. Lou Misner might get his first road start on Tuesday, as Mark Saxby is questionable.

The Comets will look to keep the momentum going from Saturdays win into Tuesdays match with the first game of 2020 on Saturday against the Milwaukee Wave looming.

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Kansas City Comets end 2019 with New Years Eve clash in St. Louis - The Blue Testament

Lady Comets win tourney in Pottsville – The Abington Journal

December 26, 2019

Abington Heights and Lackawanna Trail each won their second straight Lackawanna League wrestling matches to share the early divisional leads with their likely top competition.

Abington Heights and Delaware Valley, the teams that finished tied for first last season, share the Division 1 lead at 2-0.

There are also two 2-0 teams, Lackawanna Trail and defending champion Blue Ridge, at the top of Division 2.

The Comets and Lions went virtually untested by a pair of short-handed teams.

Abington Heights 72, Valley View 10

Abington Heights rolled over host Valley View with the help of six forfeits.

The match started with four of those forfeits and the only one by Abington Heights to put the Comets in front, 24-6, before wrestling began.

After Valley View won at 120 pounds to cut the deficit to 24-10, Abington Heights rolled through six straight pins in a total of 7:55 before receiving its final two forfeits.

Sam Stevens and Ty Wilmot got it started with 32- and 25-second pins at 126 and 132.

Hutch Lynott (138), James Brown (152) and Jacob Gilmore (160) also had first-period pins. Sal Schaivone won in the second period at 145.

The match was the only one of the week for the Comets, who are 5-2 overall. They host Delaware Valley in the league finale Jan. 22.

Lackawanna Trail 78, Mountain View 0

The Lions started with three forfeits and ended with six more at Mountain View.

In between, they swept all five bouts on the mat, led by first-period pins from Seth Ross and Tyler Rozanski at 152 and 170.

Michael Bluhm added a pin at 138.

Dalton Klinges pulled out a 4-3 decision over Nathan Ofalt at 145 and Kody Cresswell also won a decision at 160.

BOYS BASKETBALL

Abington Heights lost twice in three days in games that matched multi-year defending division and district champions against each other.

The Comets, from Lackawanna League Division 1 and District 2 Class 5A, played Wyoming Seminary, the defending Wyoming Valley Conference overall and District 2 Class 3A champion, Wednesday, then took on Hazleton Area, the reigning WVC Division 1 and District 2-4 Class 6A Subregional champion, Friday in a pair of home games.

Hazleton Area 45, Abington Heights 42

Scotty Campbells 3-pointer from the left corner with 1.9 seconds left lifted Hazleton Area to the victory after Abington Heights had rallied from eight points behind in the fourth quarter.

The Comets tied the game in the final minute on a Corey Perkins basket in the lane.

Perkins finished with 14 points.

Phil Johnson, who had 10 of his 12 points in the second half, and Kyle Nealon each hit 3-pointers during the fourth-quarter comeback.

Harry Johnson added eight points.

Perkins had seven of his points in the first quarter to give Abington Heights a 14-12 lead.

The Comets slipped to 3-3.

Lackawanna Trail 53, Old Forge 44

Richard Helbing scored 20 points and Josh Rzucidlo added 17 to lead Lackawanna Trail past visiting Old Forge Thursday.

Nico Berrios hit a 3-pointer in each of the first three quarters, then went 5-for-5 from the line to add 14 points for the Lions.

While the teams it will play against in Lackawanna League Division 4 are a combined 1-24 against outside competition during non-league play, the Lions are off to a 4-2 start.

Wyoming Seminary 53, Abington Heights 46

Jeremy Callahan scored 21 points Dec. 18 to lead Wyoming Seminary to the victory.

Kyle Nealon drained five 3-pointers while scoring 17 points for Abington Heights. Corey Perkins added 10 points in the loss.

Lackawanna Trail 45, Towanda 30

Richard Helbing scored 10 of his 20 points to key a 16-7 second quarter that put Lackawanna Trail ahead in the Dec. 16 road game.

Nico Berrios added 13 points and Josh Rzucidlo had 10.

GIRLS BASKETBALL

Abington Heights split two games to end the week with a 5-2 record.

Holy Cross 52, Abington Heights 48

Abbey Lentowski scored 19 points Saturday night as host Holy Cross won a showdown between defending District 2 champions.

The Class 2A Lady Crusaders also got 16 points from Kaci Kranson to improve to 4-1 and beat the Class 5A Lady Comets.

Rachel McDonald made three 3-pointers and led Abington Heights with 17 points.

Abington Heights 69, Mountain View 25

Clair Marion scored nine points in the first quarter and Allison Dammer had eight in the second as Abington Heights piled up 39 first-half points at Mountain View Friday night.

Marion finished with 15 points, Rachel McDonald had 11 and Dammer had 10. Sadie Henzes made three 3-pointers while adding nine.

The win was the fifth straight for the Lady Comets.

Tunkhannock 46, Lackawanna Trail 30

Megan Gatto scored 11 points Friday when Lackawanna Trail (0-5) produced its highest-scoring game of the season while falling to 0-5 with the home loss.

Northwest 43, Lackawanna Trail 23

Megan Gatto had eight points for Lackawanna Trail during the Dec. 18 road loss.

Abington Heights Corey Perkins gets blocked by Williamsports Nassir Jones (2) during a game earlier this month.

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Lady Comets win tourney in Pottsville - The Abington Journal

Huge fireballs from dead comet will soar across sky TONIGHT how to spot the Quadrantid meteor shower – The Sun

THE FIRST meteor shower of 2020 is upon us.

Avid stargazers should be able to spot the annual Quadrantid meteor shower tonight and into the early hours of Saturday morning.

2

Up to 60 meteors an hour are expected to burn across the sky in a spectacular display.

The Quadrantid meteor shower usually starts in late December and lasts until early January but the best time to see it will be January 3 and 4.

This is because tonight is when the meteor shower will reach its peak.

The celestial display occurs because the Earth passes through the trail of an asteroid or possible rock comet called 2003 EH1.

2

This space rock is travelling through our Solar System at 26 miles per second.

Meteors are pieces of debris that have broken off asteroids or comets.

If this debris comes into contact with the Earth's atmosphere at speed then they burn up and become visible as bright streaks across the sky.

The meteor shower is set to peak later on tonight and in the early hours of tomorrow morning.

Some experts think your best chance of seeing the bright display will be just before sunrise on Saturday 4.

Sunrise in London will be at 8:06am.

You'll want to be outside at least an hour before this so your eyes have a chance to adjust to the dark.

The meteor shower should be visible from most of the countries in the Northern Hemisphere.

You'll need to look north-east and below the handle of the Big Dipper constellation.

As with any meteor shower, there is no guarantee you'll definitely be able to spot it as sometimes it just comes down to the luck of being in the right place at the right time.

The Royal Observatory advise: "For the best conditions, you want to find a safe location away from street lights and other sources of light pollution.

"The meteors can be seen in all parts of the sky, so its good to be in a wide-open space where you can scan the night sky with your eyes."

What's the difference between an asteroid, meteor and comet?

Here's what you need to know, according to Nasa...

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In other space news, an amazing SpaceX video reveals how the Crew Dragon capsule will fire astronauts to the ISS.

Scientists want to move the Sun and our Solar System to save Earth from killer asteroids.

And, "Super-Puff" planets outside our Solar System have the density of candy floss, says Nasa

Will you be looking out for the Quadrantids? Let us know in the comments...

We pay for your stories! Do you have a story for The Sun Online Tech & Science team? Email us at tech@the-sun.co.uk

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Huge fireballs from dead comet will soar across sky TONIGHT how to spot the Quadrantid meteor shower - The Sun

More than Comets: Inside the Adirondack Bank Center – Utica Observer Dispatch

When most people think of the Adirondack Bank Center, they think of the Utica Comets.

While the American Hockey League team is the headlining act, the arena is anything but empty when theyre not in town. Most days, the first skaters hit the ice at 6:30 a.m. and a steady stream of teams use the facility until it closes at 11 p.m., said Ray Meyers, Adirondack Bank Center assistant general manager.

The arena is shared by the Comets, two Utica College ice hockey teams, a National Collegiate Development Conference team and 13 youth hockey teams, as well as the Utica City FC soccer team. Its a lot of activity to be contained within a single facility and Meyers said scheduling is a big challenge.

The Adirondack Bank Center has about 470 total employees, counting part-time and restaurant staff. There are only 15 maintenance staff employees, however, and ensuring proper staffing and time off between shifts can be tough, Meyers said.

A lot of what we do is a team effort; theres not one particular individual job, Meyers said. Its a collaborative effort to get it done.

The responsibilities for maintenance staff are varied and around the clock. Any given day, theyre responsible for 11 ice cuts during hours of operation.

Donald Bienkowski, the maintenance manager and an employee at the center for 19 years, watches the Comets practice while alongside the ice cutting machine he drives. He said he measures the thickness of the ice every Monday and weighs factors that can affect ice quality, including outside air temperature.

While he hasnt cut ice during a Comets game this season, Bienkowski said he works during the day shift, when theres a team on the ice almost all the time.

You see a lot of hockey, thats for sure, Bienkowski said.

Despite the demands of the job, Bienkowski said there are good workers at the Adirondack Bank Center and the work is fun.

Its exciting to work here, he said. The people are great.

The entire maintenance staff faces their biggest challenge when changing the arena surface from ice to something else, such as the turf field for Utica City FC. Its an all-night process, Bienkowski said.

For soccer games, the ice needs to be covered by the turf and a lower tier of seating is pushed back to make a field-level beer garden. All of the glass is removed and some of the boards, to allow for recessed goals and team-specific advertising sponsors.

Meyers said the changeover occurs at night, with maintenance employees working until 7 a.m., then returning by 4 p.m. the next day to do it again.

The addition of the Adirondack Bank Centers new neighbor, the Nexus Center, wont alleviate the late-night changeovers between soccer and hockey, Meyers said. The 170,000-square-foot proposed facility will change some of the dynamics of use at the Aud, though.

The Nexus Center, which may receive up to $22 million in state funds, is expected to have three sheets of ice. Meyers said the centers location along the Thruway will help draw tournaments.

Facilities like this exist in Marlborough, Massachusetts, Lake Placid, Buffalo, Philadelphia, said Lindsay Mogle, vice president of communications for the Utica Comets. So if you look at those on a map, were the central hub to all of that.

With more ice availability once the Nexus Center is built, youth hockey is likely to grow, Meyers said. There currently are youth locker rooms and other amenities in the Adirondack Bank Center, but only one place to play.

Youth hockey wont be the only beneficiary of the Nexus Center, however. If the Comets are displaced due to a concert or other event, as happened once with a police funeral, they have to find another place to practice, Meyers said.

Now theyll be able to practice on a different sheet of ice right here and wont have to travel to New Hartford or Whitesboro to get ice, he said.

One current tenant of the Adirondack Bank Center, the Utica College womens ice hockey team, is still waiting to see the full impact of the Nexus Center. Coach Dave Clausen said its unknown how scheduling will unfold with the new center, but everyone will benefit from the additional ice slots.

An expansion of facilities is going to be exciting, Clausen said.

The additional ice will benefit those using the facility, but it will also impact existing maintenance employees.

It is going to be a lot more demand on our staff, having to maintain three more sheets of ice on top of the one were doing now, Meyers said. So our drivers will basically be going from one rink to another rink to the next rink all day long.

The proposed Nexus Center follows the revitalization of the Adirondack Bank Center, which was expanded, renovated and rebranded in 2017. The facility received a 26,000-square-foot expansion, including a new entrance, executive suites and a new womens bathroom as part of a state-funded $10.55 million project.

The Utica Memorial Auditorium was built by the City of Utica in 1959 on land donated by the state. The cable-supported roof structure was the first of its kind and the building provided inspiration for Madison Square Garden, the home of the New York Knicks and New York Rangers.

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More than Comets: Inside the Adirondack Bank Center - Utica Observer Dispatch

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

In Depth | Comets NASA Solar System Exploration

OverviewIn the distant past, people were both awed and alarmed by comets, perceiving them as long-haired stars that appeared in the sky unannounced and unpredictably. Chinese astronomers kept extensive records for centuries, including illustrations of characteristic types of comet tails, times of cometary appearances and disappearances, and celestial positions. These historic comet annals have proven to be a valuable resource for later astronomers.

We now know that comets are leftovers from the dawn of our solar system around 4.6 billion years ago, and consist mostly of ice coated with dark organic material. They have been referred to as "dirty snowballs." They may yield important clues about the formation of our solar system. Comets may have brought water and organic compounds, the building blocks of life, to the early Earth and other parts of the solar system.

Where Do Comets Come From?

As theorized by astronomer Gerard Kuiper in 1951, a disc-like belt of icy bodies exists beyond Neptune, where a population of dark comets orbits the Sun in the realm of Pluto. These icy objects, occasionally pushed by gravity into orbits bringing them closer to the Sun, become the so-called short-period comets. Taking less than 200 years to orbit the Sun, in many cases their appearance is predictable because they have passed by before. Less predictable are long-period comets, many of which arrive from a region called the Oort Cloud about 100,000 astronomical units (that is, about 100,000 times the distance between Earth and the Sun) from the Sun. These Oort Cloud comets can take as long as 30 million years to complete one trip around the Sun.

Each comet has a tiny frozen part, called a nucleus, often no larger than a few kilometers across. The nucleus contains icy chunks, frozen gases with bits of embedded dust. A comet warms up as it nears the Sun and develops an atmosphere, or coma. The Sun's heat causes the comet's ices to change to gases so the coma gets larger. The coma may extend hundreds of thousands of kilometers. The pressure of sunlight and high-speed solar particles (solar wind) can blow the coma dust and gas away from the Sun, sometimes forming a long, bright tail. Comets actually have two tailsa dust tail and an ion (gas) tail.

Most comets travel a safe distance from the Suncomet Halley comes no closer than 89 million kilometers (55 million miles). However, some comets, called sungrazers, crash straight into the Sun or get so close that they break up and evaporate.

Exploration of Comets

Scientists have long wanted to study comets in some detail, tantalized by the few 1986 images of comet Halley's nucleus. NASA's Deep Space 1 spacecraft flew by comet Borrelly in 2001 and photographed its nucleus, which is about 8 kilometers (5 miles) long.

NASA's Stardust mission successfully flew within 236 kilometers (147 miles) of the nucleus of Comet Wild 2 in January 2004, collecting cometary particles and interstellar dust for a sample return to Earth in 2006. The photographs taken during this close flyby of a comet nucleus show jets of dust and a rugged, textured surface. Analysis of the Stardust samples suggests that comets may be more complex than originally thought. Minerals formed near the Sun or other stars were found in the samples, suggesting that materials from the inner regions of the solar system traveled to the outer regions where comets formed.

Another NASA mission, Deep Impact, consisted of a flyby spacecraft and an impactor. In July 2005, the impactor was released into the path of the nucleus of comet Tempel 1 in a planned collision, which vaporized the impactor and ejected massive amounts of fine, powdery material from beneath the comet's surface. En route to impact, the impactor camera imaged the comet in increasing detail. Two cameras and a spectrometer on the flyby spacecraft recorded the dramatic excavation that helped determine the interior composition and structure of the nucleus.

After their successful primary missions, the Deep Impact spacecraft and the Stardust spacecraft were still healthy and were retargeted for additional cometary flybys. Deep Impact's mission, EPOXI (Extrasolar Planet Observation and Deep Impact Extended Investigation), comprised two projects: the Deep Impact Extended Investigation (DIXI), which encountered comet Hartley 2 in November 2010, and the Extrasolar Planet Observation and Characterization (EPOCh) investigation, which searched for Earth-size planets around other stars on route to Hartley 2. NASA returned to comet Tempel 1 in 2011, when the Stardust New Exploration of Tempel 1 (NExT) mission observed changes in the nucleus since Deep Impact's 2005 encounter.

How Comets Get Their Names

Comet naming can be complicated. Comets are generally named for their discoverereither a person or a spacecraft. This International Astronomical Union guideline was developed only in the last century. For example, comet Shoemaker-Levy 9 was so named because it was the ninth short-periodic comet discovered by Eugene and Carolyn Shoemaker and David Levy. Since spacecraft are very effective at spotting comets many comets have LINEAR, SOHO or WISE in their names.

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In Depth | Comets NASA Solar System Exploration

NASA Issues Warning Over Pack Of Comets That Can Wipe Out The Human Race – The Buzz Paper

Another type of celestial killer thats the packs more of a punch than asteroids, Nasa has warned and continuously researching over it for since past few months.

NASA has reported that Pack of Comets could appear out of nowhere and can collapse wiping out every species living on the Earth.

And even some scientists have now believed that made of ice, gas, and rock. Comets are often likened to dirty snowballs that have wiped the dinosaurs species rather than the asteroids. NASA expert said in one of his interviews early December that Comets are essentially asteroids which are heavy on ice

Throughout history, comets have been seen as wicked, predicting terrible events, such as hunger, plague, and war. This fear of comets is also present in most modern times. In 1910, word spread that Halleys comets tail is a deadly gas that will cover the Earth. Anti-kite bullets and gas masks did an energetic business despite the guarantees of most astronomers.

You are likely to kill comets in eccentric orbits that increase your risk of slipping on Earth. Comets may appear in the first months or years of impact, meaning that we may have very little time to destroy or destroy an object on a collision course with Earth.

Objects called long-term comets present a particular challenge. They follow huge orbits, revolve around the Sun for more than 200 years, and their movements are much harder to predict.

Those pieces will rain automatically, destroy cities and cause devastating for all civilization. Anyone who has lived through this initial bombardment would be involved in a difficult battle to survive since the impact would throw so much dust and debris that sunlight is blocked and planets cannot grow.

NASA wrote earlier: it would have been disastrous if it had an object of a similar size to hit the Earth. The effect can send dust and debris to the sky, creating a fog that will calm the atmosphere and absorb sunlight, covering the entire planet in the dark. If the fog lasts a long time, the life of the plants will die, along with those and animals that depend on it to survive.

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NASA Issues Warning Over Pack Of Comets That Can Wipe Out The Human Race - The Buzz Paper

Will the Utica Comets be playing an outdoor game? – Utica Observer Dispatch

The possibility of a professional outdoor hockey game in the Mohawk Valley took a considerable step Thursday.

The Mohawk Valley Regional Economic Development Council was awarded $82.7 million for 81 economic development projects, state officials announced Thursday.

Among those projects is a proposal for the Mohawk Valley Garden group to hold a "Winter Festival Sporting Event" as part of the 25th anniversary of Romes Griffiss Business and Technology Park and the grand opening of the Nexus Center in downtown Utica, according to the awards listing.

In development on Whitesboro Street next to the Adirondack Bank Center, the Nexus Center is touted as a tournament-based recreation facility primarily for hockey, box lacrosse and soccer.

The "Winter Festival Sporting Event" project was awarded $345,000. The listing mentions the event would include a "Utica Comets (American Hockey League) outdoor game, an NCAA Division III game featuring Utica College, a (Major Arena Soccer League) match featuring Utica City FC, and other local and regional competitions."

No further details, including dates for the possible events, were announced.

Rome Mayor Jacqueline Izzo said that the bulk of the $345,000 would be used for an outdoor game at the Griffiss Business Park. The money would fund a portable rink and seating areas, with everything set up near one of the hangars, Izzo said. She referred to this as retrofitting the area for the game.

"It sounds like a really exciting event for the community," Izzo said. "Outdoor hockey events are the rage right now."

Rob Esche, president of Mohawk Valley Garden, could not be reached for comment Thursday. Mohawk Valley Garden is an overall organization that manages the Utica Comets and Utica City FC, among others.

Esche told the Observer-Dispatch in 2017 that he was looking to have an outdoor game in the Utica area, but noted there were challenges in finding a suitable venue. He said at the time he had spoken with Syracuse Crunch owner Howard Dolgon about being included in an outdoor game, but those plans didnt come to fruition.

"We would love to compete on that type of stage," Esche said in January 2017. "I think it would be a great experience. Im all for building the sport in Central New York and building the sport as a whole. ..."

AHL Vice President of Communications Jason Chaimovitch said the scheduling process hasnt started yet for the 2020-21 season. That process usually starts early in the year, he said. The AHL would work with the Comets for the possible game, he said.

"We would help in making sure it gets scheduled," Chaimovitch said. "It is not on our radar, yet."

There have been 10 outdoor games in the AHLs history. Most notably, the Syracuse Crunch put on an outdoor game in 2010 at the New York State Fairgrounds. The Rochester Americans also played at Frontier Field in 2013.

Utica College Athletic Director Dave Fontaine and mens hockey coach Gary Heenan said they didnt have any details surrounding the schools possible involvement.

Notably, UC was included as part of the Frozen Dome Classic in 2014 when the Comets and Crunch played in Syracuse.

Contact reporter Ben Birnell at 315-792-5032 or follow him on Twitter @OD_Birnell.

Observer-Dispatch reporter Edward Harris contributed to this story.

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Will the Utica Comets be playing an outdoor game? - Utica Observer Dispatch

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


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