Tuesday, April 28At magnitude 8.4, Vesta is within easy reach of most binoculars. To find it, locate Aldebaran, the brightest star in Taurus, and draw an imaginary line northeast. First, youll hit the open star cluster NGC 1647, which contains several dozen scattered 8th- to 11th- magnitude stars. Continue that line roughly the same distance to the northeast and begin scanning for Vesta, which is slowly advancing through a region with few background stars. Try this exercise two or three nights in a row to find the spot that has moved thats the asteroid youre looking for.

Wednesday, April 29Mars remains an ideal morning target to catch before sunrise. The Red Planet glows at magnitude 0.4 in the southeastern sky, positioned midway between two 4th-magnitude stars: Iota () and Gamma () Capricorni. Mars is nearly 20 above the horizon an hour before sunrise.

Mars also stands at the center of a planetary gathering. Look west to find Saturn nearly 19 away, with Jupiter just 5 farther in the same direction. These two solar system giants shine at magnitude 0.6 and 2.4, respectively. Telescopic observers and imagers can add a dwarf planet to the mix: Pluto is just 2 southwest of Jupiter, glinting faintly at magnitude 14.

Turn your telescope 30 east of Mars to glimpse magnitude 8 Neptune. The ice giant is still low on the eastern horizon, rising higher as the sky brightens with the coming dawn. See how long you can track it before the bright sky hides it from view.

Thursday, April 30First Quarter Moon occurs at 4:38 P.M. EDT. An hour after sunset, our satellite stands high in the southwestern sky in the faint constellation Cancer the Crab. In the moonlit sky, you might have better luck spotting Gemini the Twins and their bright luminaries, Castor and Pollux, to the west. Look east of the Moon to find Leo the Lion, with his brightest star Regulus, and follow the ecliptic farther east to reach Virgo the Maiden, whose brightest star is Spica. This blue-white magnitude 1 star is not one star, but two however, the stars are so close that they cannot be split visually. Instead, astronomers discovered Spicas dual nature by noticing that as one star orbits the other, gravitys effects shift the light we see from the star slightly red and then blue over time.

The larger of the two, Spica A, is roughly seven times wider than our Sun and 10 times as massive. Most of the light we see from the star comes from this component. The smaller Spica B is a little less than four times wider than the Sun and seven times as massive.

Friday, May 1 The Eta Aquariids have been slowly ramping up since last week and will peak in another few days. Its not one of the years best meteor showers, due to its low-altitude radiant in the Northern Hemisphere and low predicted rate of just 10 meteors per hour at its peak. But with Mars hanging nearby and a still-crescent Moon in the sky, its worth trying to catch a few shooting stars this morning.

Find the darkest skies possible and spend some time scanning overhead. Try concentrating on a spot away from the constellation Aquarius, where the showers meteors originate. You may only see five or so Eta Aquariid meteors an hour, but this is also a great chance to relax beneath the stars and get to know the morning sky much better.

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The Sky This Week from April 24 to May 1 - Astronomy Magazine

Countinguniverses ought to be easy. By definition, you can stop at 1.

Troubleis, definitions change. A century ago, the universe was defined as the MilkyWay galaxy. Heretics who disagreed had long been ridiculed until sciencestaged what became known as the Great Debate, on April 26, 100 years ago. Onthat date, American astronomers HarlowShapley and HeberCurtis articulated opposing views on the scope of the cosmos.

Todayastronomers know that the Milky Way, huge as it is, is a mere drop in thecosmic bucket. Just as the sun is only one of 100 billion or so stars swirlingwithin the Milky Ways pinwheel disk, the Milky Way is only one of hundreds ofbillions of such galaxies inhabiting a vast, expanding bubble of space.

Butin 1920, conventional wisdom dictated that the Milky Way was alone. Mostexperts insisted that the fuzzy patches of light known as nebulae residedwithin the Milky Way. Nebulae with a spiral structure might be solar systems inthe making, some astronomers suggested.

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Othersinsisted that the nebulae were far, far away, well beyond the Milky Waysborders. In fact, the heretics argued, the nebulae (at least some) containedstars in quantities comparable to our galaxy, and deserved recognition asisland universes.

Actually,the island universe idea had been a popular explanation for the nebulae in themid-19th century. (American astronomer OrmsbyMacKnight Mitchel coined the island universe label inthe 1840s, a translation from a German article referring to the nebulae as Weltinseln.)But by centurys end, the astronomical consensus had affirmed the Milky Way asthe sole and rightful universe. Irish astronomer and author Agnes Clerkedeclared in 1890 that no competent thinker believed the nebulae to be galaxiescomparable to the Milky Way. She later wrote that the island universe theoryhad passed into the realm of discarded and half-forgotten speculations.

Butduring the first two decades of the 20th century, new astronomical observationsraised doubts. Curtis, for one, maintained that the evidence favored islanduniverses. But Shapley insisted that the nebulae could not be far enough awayto be outside the Milky Way. He cited measurements (by Adriaan van Maanen) ofmotion of the spiral arms within some nebulae; such motion would beundetectable if the nebulae were actually distant galaxies.

In1919, leaders of the National Academy of Sciences decided it would be fun to holda debate on the dispute at the academys meeting the following April.

Technically,the topic of the debate was to be on the distance scale of the universe. Onthat issue, Curtis was the conservative and Shapley was the heretic. Curtismaintained the more traditional view that the visible Milky Way stretched onlyabout 30,000 light-years across at most, and was possibly much smaller. Shapleythought that the Milky Way had a diameter of 300,000 light-years (much bigger eventhan todays estimate of roughly 100,000 light-years or so).

AlthoughShapleys view of the Milky Ways size was radical, it did support theconsensus view opposing island universes.

If, as Shapley maintained,the Galaxy was much larger than had previously been thought, it would be moredifficult for Curtis to sustain the claim that the spiral nebulae wereindependent island universes, historian Michael Hoskin observed in a 1976 paper analyzing the debate.

Asit turned out, the debate was nothing that CNN would had televised. Eachastronomer just presented a 40-minute talk. Shapley, who went first, read froma typewritten script. Curtis, the better speaker, showed slides, a more powerfulway to make his point.

Shapleyrecounted a potpourri of recent astronomical observations, barely mentioningthe island universe theory. He insisted that Curtis interpretation of the observationsrequired abandoning the very foundations of modern astrophysics.But he acknowledged that if the Milky Way was really small, the island universeidea just maybe could be right.

Ifthe galactic system is as large as I maintain, the spiral nebulae can hardly becomparable galactic systems, Shapley declared. If it is but one-tenth aslarge, theremightbe a good opportunity for the hypothesisthat our galactic system is a spiral nebula, comparable in size with the otherspiral nebulae, all of which would then be island universes of stars.

Curtispresented data supporting his view of a smaller Milky Way, citing variousestimates of its diameter ranging from 10,000 light-years to 30,000light-years. He argued that the analysis of light from spiral nebulae indicatedthat they were clusters of stars (with similar features to the spectrum oflight from the Milky Way itself). The spectrum of the spiral nebulae offers nodifficulties in the island universe theory of the spirals, Curtis stated.Subsequent slides further built the case for the spirals as island universes.

Moredetailed arguments (deviating considerably from the original talks) appearedthe next year inpapers by Shapley and Curtis published jointly under the title TheScale of the Universe in the Bulletin of the National Research Council.Resolution of the debate came two years later: Astronomer Edwin Hubbledemonstrated that the Andromedanebula was truly an island universe full of stars at a distance farexceeding even Shapleys generous estimate of the Milky Ways girth.

Facedwith new findings, Shapley had to concede. When a letter arrived from Hubblereporting the Andromeda results, Shapley remarked: Here is the letter thatdestroyed my universe.

Shapleyhad been misled by van Maanens measurements they simply turned out to bewrong. Shapley said later that van Maanen was his friend, so of course he believed him,astronomer Virginia Trimble commented in a 1995 discussion of the debate.

ButShapley had not been entirely defeated. For on another important point, he wasright, and Curtis was wrong. In his smaller Milky Way, Curtis placed the sunvery near the center, as astronomical consensus dictated. Around the turn ofthe century, astronomer Simon Newcomb had wondered about that consensus, though,pointing out that ancient astronomers believed with equal confidence that theEarth sat at the center of the universe. Shapley declared that Newcomb wasright to be skeptical.

We havebeen victimized by the chance position of the sun near the center of asubordinate system, and misled by the consequent phenomena, to think that weare Gods own appointed, right in the thick of things, Shapley said at the1920 debate in much the same way ancient man was misled, by the rotation ofthe earth to believe that even his little planet was the center of theuniverse.

Today astronomers all know that Shapley was right about the sun; it is substantially displaced from the galactic center. And everybody knows that Curtis was also right: The Milky Way home to sun, Earth and humankind is not a single universe unto itself, but one of a myriad upon myriad of other galaxies no longer known as island universes, as the definition of universe had to be changed.

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A century ago, astronomys Great Debate foreshadowed todays view of the universe - Science News

"Clearly, Fomalhaut b was doing things a bona fide planet should not be doing," Gspr said.

The last straw for Fomalhaut b was when researchers looked at Hubble images from 2014, which revealed the object had vanished altogether. Though there could be reasons why an exoplanet fades, they certainly dont just disappear.

This led researchers to conclude that Fomalhaut b was nothing more than a planetary mirage namely, an energetic cloud of debris blasted from a collision between two large icy objects. Then, as the cloud dispersed, the faux-planet Fomalhaut b dissolved into nothingness. Based on the evolving shape and location of the debris, the researchers estimate the original colliding bodies were each likely a mix of ice and dust measuring about 125 miles (200 kilometers) across.

Unfortunately, Hubble seems to have been late for the main event, as the researchers think the crash happened right before the telescope began observing the system in 2004. But just detecting the results of such a violent cosmic event is exciting, they say. According to the researchers calculations, such a massive collision may only happen once every 200,000 years in a given system.

Astronomers hope to further study the Fomalhaut system with the upcoming the James Webb Space Telescope during its first year of operations. The future observations will hopefully answer questions about Fomalhauts asteroid belt, as well as about any legitimate planets actually orbiting the star.

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Hubble watches a suspected exoplanet disappear before its very eyes - Astronomy Magazine

The Histories by Herodotus (484BC to 425BC) offers a remarkable window into the world as it was known to the ancient Greeks in the mid fifth century BC. Almost as interesting as what they knew, however, is what they did not know. This sets the baseline for the remarkable advances in their understanding over the next few centuries simply relying on what they could observe with their own eyes.

Herodotus claimed that Africa was surrounded almost entirely by sea. How did he know this? He recounts the story of Phoenician sailors who were dispatched by King Neco II of Egypt (about 600BC), to sail around continental Africa, in a clockwise fashion, starting in the Red Sea. This story, if true, recounts the earliest known circumnavigation of Africa, but also contains an interesting insight into the astronomical knowledge of the ancient world.

The voyage took several years. Having rounded the southern tip of Africa, and following a westerly course, the sailors observed the Sun as being on their right hand side, above the northern horizon. This observation simply did not make sense at the time because they didnt yet know that the Earth has a spherical shape, and that there is a southern hemisphere.

A few centuries later, there had been a lot of progress. Aristarchus of Samos (310BC to 230BC) argued that the Sun was the central fire of the cosmos and he placed all of the then known planets in their correct order of distance around it. This is the earliest known heliocentric theory of the solar system.

Unfortunately, the original text in which he makes this argument has been lost to history, so we cannot know for certain how he worked it out. Aristarchus knew the Sun was much bigger than the Earth or the Moon, and he may have surmised that it should therefore have the central position in the solar system.

Nevertheless it is a jawdropping finding, especially when you consider that it wasnt rediscovered until the 16th century, by Nicolaus Copernicus, who even acknowledged Aristarchus during the development of his own work.

One of Aristarchus books that did survive is about the sizes and distances of the Sun and Moon. In this remarkable treatise, Aristarchus laid out the earliest known attempted calculations of the relative sizes and distances to the Sun and Moon.

It had long been observed that the Sun and Moon appeared to be of the same apparent size in the sky, and that the Sun was further away. They realised this from solar eclipses, caused by the Moon passing in front of the Sun at a certain distance from Earth.

Also, at the instant when the Moon is at first or third quarter, Aristarchus reasoned that the Sun, Earth, and Moon would form a right-angled triangle.

As Pythagoras had determined how the lengths of triangles sides were related a couple of centuries earlier, Aristarchus used the triangle to estimate that the distance to the Sun was between 18 and 20 times the distance to the Moon. He also estimated that the size of the Moon was approximately one-third that of Earth, based on careful timing of lunar eclipses.

While his estimated distance to the Sun was too low (the actual ratio is 390), on account of the lack of telescopic precision available at the time, the value for the ratio of the size of the Earth to the Moon is surprisingly accurate (the Moon has a diameter 0.27 times that of Earth).

Today, we know the size and distance to the moon accurately by a variety of means, including precise telescopes, radar observations and laser reflectors left on the surface by Apollo astronauts.

Eratosthenes (276BC to 195 BC) was chief librarian at the Great Library of Alexandria, and a keen experimentalist. Among his many achievements was the earliest known calculation of the circumference of the Earth. Pythagoras is generally regarded as the earliest proponent of a spherical Earth, although apparently not its size. Eratosthenes famous and yet simple method relied on measuring the different lengths of shadows cast by poles stuck vertically into the ground, at midday on the summer solstice, at different latitudes.

The Sun is sufficiently far away that, wherever its rays arrive at Earth, they are effectively parallel, as had previously been shown by Aristarchus. So the difference in the shadows demonstrated how much the Earths surface curved. Eratosthenes used this to estimate the Earths circumference as approximately 40,000km. This is within a couple of percent of the actual value, as established by modern geodesy (the science of the Earths shape).

Later, another scientist called Posidonius (135BC to 51BC) used a slightly different method and arrived at almost exactly the same answer. Posidonius lived on the island of Rhodes for much of his life. There he observed the bright star Canopus would lie very close to the horizon. However, when in Alexandria, in Egypt, he noted Canopus would ascend to some 7.5 degrees above the horizon.

Given that 7.5 degrees is 1/48th of a circle, he multiplied the distance from Rhodes to Alexandria by 48, and arrived at a value also of approximately 40,000km.

The worlds oldest surviving mechanical calculator is the Antikythera Mechanism. The amazing device was discovered in an ancient shipwreck off the Greek island of Antikythera in 1900.

The device is now fragmented by the passage of time, but when intact it would have appeared as a box housing dozens of finely machined bronze gear wheels. When manually rotated by a handle, the gears span dials on the exterior showing the phases of the Moon, the timing of lunar eclipses, and the positions of the five planets then known (Mercury, Venus, Mars, Jupiter, and Saturn) at different times of the year. This even accounted for their retrograde motion an illusionary change in the movement of planets through the sky.

We dont know who built it, but it dates to some time between the 3rd and 1st centuries BC, and may even have been the work of Archimedes. Gearing technology with the sophistication of the Antikythera mechanism was not seen again for a thousand years.

Sadly, the vast majority of these works were lost to history and our scientific awakening was delayed by millennia. As a tool for introducing scientific measurement, the techniques of Eratosthenes are relatively easy to perform and require no special equipment, allowing those just beginning their interest in science to understand by doing, experimenting and, ultimately, following in the foot steps some of the first scientists.

One can but speculate where our civilisation might be now if this ancient science had continued unabated.

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Four amazing astronomical discoveries from ancient Greece - The Conversation UK

The Solar System has been here for a long time. So, when 'Oumuamua was spotted in 2017, it was almost a dead cert it wasn't the only object from interstellar space to visit us over that 4.57 billion-year history. Then comet 2I/Borisov showed up last year. That basically clinched it.

But where are the rest of our interstellar visitors? We'll probably find a few more flying in from the wilds in the coming years. And, according to new research, a whole bunch of interstellar asteroids have been hanging out right here in the Solar System for a very long time.

Based on how they move around the Sun, a team of researchers has identified 19 asteroids they think were captured from another star, way back when the Solar System was just a few million years old.

Back then, astronomers believe, the Sun was part of a stellar nursery, a cluster of stars being born close together of the same cloud of gas and dust.

"The close proximity of the stars meant that they felt each others' gravity much more strongly in those early days than they do today," explained astronomer and cosmologist Fathi Namouni of the Observatoire de la Cte d'Azur in France.

"This enabled asteroids to be pulled from one star system to another."

Fathi and his colleague astronomer Helena Morais of the Universidade Estadual Paulista in Brazil found their first permanent interstellar resident in 2018. They were looking into a group of asteroids called the Centaurs, which hang out between Jupiter and Neptune, and often have really weird orbits.

One asteroid called 2015 BZ509 - later named Kaepaokaawela - was on a weirder orbit than most - exactly the same as Jupiter's, but in the opposite direction, or retrograde. If it was native to the Solar System, it should have been travelling in the same direction as everything else, so the team ran simulations to discover its origins.

They found that Kaepaokaawela's most likely origin was interstellar space, and it had been captured into the Solar System 4.5 billion years ago.

In the new study, the team examined Centaurs and trans-Neptunian objects with high orbital inclination relative to the orbital plane of the planets, sometimes bringing them close to a polar orbit. And, like Kaepaokaawela, some of these objects also have retrograde orbits.

"With moderate to high eccentricities, Centaurs' orbits may be inclined by a few degrees with respect to the Solar System's invariable plane to almost 180 resulting in retrograde motion," the researchers wrote in their paper.

"Their orbital features are often taken as a sign of their violent past in the Solar System, a notion reinforced by their so-called instability. If a Centaur orbit is integrated forward or backward in time, it will invariably either hit the Sun, the planets, or be ejected from the Solar System."

The study included 17 Centaurs with orbital inclinations greater than 60 degrees, and two objects that orbit past Neptune, or trans-Neptunian objects. The researchers used the known orbits of these objects to create multiple clones of each one to simulate their orbits back in time - arriving at 4.5 billion years ago.

At this time, the stuff in our Solar System was all more or less in a flat disc around the Sun, leftover from the young star's accretion disc. It should have all been orbiting on around the same plane, and in the same direction.

But, according to the team's simulations, these 19 asteroids weren't a part of that tidy disc. Most of the clones did indeed end up smashing into the Sun or getting kicked out of the Solar System. Fewer ended up smashing into a planet. Even fewer still maintained a stable orbit... however, since those asteroids are here today, they must have beaten the odds, according to this model.

But those that did achieve a stable orbit did not start out in the Sun's disc. Not only were they far beyond the disc's outskirts, but the orbits were perpendicular to it.

This, the researchers said, means that the probability the asteroids were captured by the Sun's gravity from outside the Solar System is higher than the probability they were born here, with the rest of the Solar System's rocks, out of the Sun's leftovers.

Future study of these rocks could help validate the team's findings; from there, they could help us identify more interstellar interlopers, which in turn could help us learn more about the formation of the Solar System, as well as other planetary systems.

"The discovery of a whole population of asteroids of interstellar origin is an important step in understanding the physical and chemical similarities and differences between Solar System-born and interstellar asteroids," Morais said.

"This population will give us clues about the Sun's early birth cluster, how interstellar asteroid capture occurred, and the role that interstellar matter had in chemically enriching the Solar System and shaping its evolution."

The research has been published in the Monthly Notices of the Royal Astronomical Society.

Link:

Astronomers Just Identified 19 More Asteroids They Think Are Interstellar - ScienceAlert

Little is more enticing than the prospect of seeing alien worlds around other starsand perhaps one day even closely studying their atmosphere and mapping their surface. Such observations are exceedingly difficult, of course. Although more than 4,000 exoplanets are now known, the vast majority of them are too distant and dim for our best telescopes to discern against the glare of their host star. Exoplanets near our solar system provide easier imaging opportunities, however. And no worlds are nearer to us than those thought to orbit the cool, faint red dwarf Proxima Centaurithe closest star to our sun at 4.2 light-years away.

In 2016 astronomers discovered the first known planet in this system: the roughly Earth-sized Proxima b. But because of its star-hugging 11-day orbit around Proxima Centauri, Proxima b is a poor candidate for imaging. Proxima c, by contrast, offers much better chances. Announced in 2019, based on somewhat circumstantial evidence, the planet remains unconfirmed. If real, it is estimated to be several times more massive than Eartha so-called super Earth or mini Neptuneand to orbit Proxima Centauri at about 1.5 times the span between Earth and the sun. Its size and distance from its star make the world a tempting target for current and near-future exoplanet-imaging projects. Now, in a new preprint paper accepted for publication in the journal Astronomy & Astrophysics, some astronomers say they mightjust might have managed to see Proxima c for the first time.

This planet is extremely interesting because Proxima is a star very close to the sun, says Raffaele Gratton of the Astronomical Observatory of Padova in Italy, who is the studys lead author. The idea was that since this planet is [far] from the star, it is possible that it can be observed in direct imaging. We found a reasonable candidate that looks like we have really detected the planet.

Last year Gratton and his team were first alerted to the possibility of imaging the planet by Mario Damasso of the Astrophysical Observatory of Turin in Italy, who was the lead author of the original paper on Proxima cs possible discovery. Damasso and his colleagues had presented evidence for Proxima cs existence based on its stars telltale wobbling, which they inferred was caused by the pull of an unseen orbiting planet. Confirming a worlds existence in this way requires seeing the same wobble occur againand againin a process that often takes many months or even years. Damasso wondered if there might be another way. Thus, he asked Gratton and his team to look through data from the SPHERE (Spectro-Polarimetric High-Contrast Exoplanet Research) instrument on the European Southern Observatorys Very Large Telescope (VLT) in Chile to see if they could actually see the planet. As soon as our paper on Proxima c was considered for publication, I contacted [Gratton] to discuss the possibility of pushing SPHERE to its limits, Damasso says. The [planetary] system is potentially so cool that it is worthy to try other techniques.

If you squint a bit while staring at the SPHERE data, a picture of the mysterious planet seems to swim into view. By focusing on Proxima cs predicted position and separation from its star within multiple, stacked infrared images from SPHERE, Gratton and his colleagues were able to pick out 19 potential appearances of the planet across several years of routine observations. Of these candidate detections, one stood out as being particularly enticing: it appeared in the images about six times brighter than their noisethat is, unwanted light from artifacts or background stars. Its a possible candidate that has a low probability of being a false alarm, says Emily Rickman of the Geneva Observatory, who is a co-author of the paper.

If that detection is genuine, it poses intriguing questions. The object believed to be the planet would be at least seven times the mass of Earthlarge enough to place it firmly beyond the super Earth category. This would definitely be some kind of mini Neptune, says Sara Seager, a professor of planetary science at the Massachusetts Institute of Technology, who was not involved in the new paper. The object also appears to be 10 to 100 times brighter than a planet of its mass should be. This luminosity, the study authors reason, couldarise from a large amount of dust surrounding the planet, perhaps in a vast ring system that is three to four times larger than that of Saturn. To some, that situation seems too strange to be true.

It would be a huge ring system around a relatively old star, says astrophysicist Bruce Macintosh of Stanford University, who also was not part of the work. Its certainly possible for things like this to exist. But for your first detection of something like this to have that massive ring system, youd have to postulate a universe in which most Neptune-sized planets have massive ring systems enormously bigger than Saturns. And that seems like an unlikely universe to live in.

If genuine, this detectionthis imagewould have profound implications for our understanding of our nearest neighboring planetary system. It would give us definitive proof of the existence of Proxima c and also provide the angle at which the planet orbits its star, relative to our ownsomething that watching a stars wobbles alone cannot provide. The detection would also all but ensure that we could soon study the planets atmosphere with a new generation of powerful observatories, such as the upcoming European Extremely Large Telescope (E-ELT) and NASAs Wide-Field Infrared Survey Telescope (WFIRST).

Perhaps more importantly, pinning down Proxima c would also likely reveal the orbital angle of Proxima b, because planets would be expected to orbit in the same plane like those in our solar system do. This information, coupled with the wobbles Proxima b raises on its star, would tell us that world must be somewhere between 1.5 and 1.8 times the mass of Earth, which would let us refine theories about its characteristics. Such a mass would strongly point to the fact [that Proxima b] is rocky, says Elizabeth Tasker, an exoplanet scientist at the Japan Aerospace Exploration Agency, who was not involved in the study. In addition to our knowledge that Proxima b orbits in its stars habitable zone, where liquid water and thus life as we know it can exist, proof that the world is rocky would catapult it to the top of any astrobiologists list of promising exoplanets.

Such spectacular possibilities, however, call for steely-eyed skepticism. Indeed, the new papers authors acknowledge there is a decent chance their image is not actually a planet at all but rather just random noise in the data. They also note that the apparent motion of their putative planet conflicts with earlier estimates of Proxima cs position, based on observations of its star made by the European Space Agencys Gaia spacecraft. Thus, other astronomers are treating the potential finding with a considerable amount of caution. Its tough for me to conclude that [this] is a decisive detection, says Thayne Currie, an exoplanet scientist at NASAs Ames Research Center, who was also not part of the work.

Unfortunately, the ongoing global shutdown in response to the COVID-19 pandemic means that the result cannot be checked for the time being, because most of the worlds observatoriesincluding the VLTare not operational. It could be [confirmed or refuted] tomorrow, but the observatories are closed, says astronomer Guillem Anglada-Escud, who led the discovery of Proxima b in 2016 and was not involved in the new study. Time is running out for an immediate follow-up: in July Proxima Centauri will pass out of view behind our sun until February 2021.

So for now, the prospect of Proxima c having been seen for the first time remains an enticing but elusive possibility. Even if it proves to be a miragean astronomical false alarmthis potential detection is unlikely to dampen enthusiasm for further studies. Other teams will try again with upcoming instruments, more advanced than SPHERE, operating on supersized telescopes such as the E-ELT. But if the detection is real, which Gratton says he is two thirds confident about, it would be a historic initial glimpse of a planet orbiting the closest start to our own. If this is true, its very exciting, says Anglada-Escud.

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Astronomers May Have Captured the First Ever Image of Nearby Exoplanet Proxima C - Scientific American

Travis Scott is about to get cosmic with Fortnite.

The Grammy-nominated rapper has teamed up with the online video game phenomenon to launch his new (and apparently space-themed) track "Astronomical" on Thursday (April 23).

"From April 23-25, blast off into a one of a kind musical journey featuring Travis Scott and the world premiere of a brand new track," Epic Games, the makers of Fortnite, wrote in an announcement. "Astronomical is an other-worldly experience inspired by Cactus Jack's creations, built from the ground up in Fortnite." (Cactus Jack is Scott's record label.)

Fans of Fortnite and Scott can jump into the game about 30 minutes before each scheduled "Astronomical" event (there are five of them) and will receive a free Astroworld Cyclone Glider and two space art loading screens just for tuning in. Fornite also launched a Travis Scott outfit for players that includes three variant skins (including one with a spacesuit helmet).

Here's when the events will occur:

"Astroworld" is the name of Scott's celebrated album and his space-themed festival that took place last November in Houston, Texas, according to our friends at Games Radar. It bears a striking similarity to Astroland, a theme park at New York City's Coney Island, which was also home to a Cyclone roller coaster at its Luna Park. (Yes, I rode it. Yes, it was awesome.)

Today (April 21) Fortnite launched a series of Astronomical Challenges for players, that will unlock a free spacesuit helmet spray, banner and a Travis Scott emote.

Scott's "Astronomical" debut isn't the first cosmic tie-in to land in the Fortnite game.

In December, the game featured a sneak peek at the "Star Wars: The Rise of Skywalker" movie, complete with a message from the Emperor, the Millennium Falcon and "Star Wars"-themed gear for players.

Last October, Epic Games ended Fortnite's first chapter with a massive black hole, which destroyed the game's island battleground for days until Chapter 2 launched. The game has also featured rocket launches, comets, meteors and other sci-fi themes in past seasons.

Email Tariq Malik attmalik@space.comor follow him@tariqjmalik. Follow us@Spacedotcom, Facebook and Instagram.

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Travis Scott will launch 'Astronomical' into the Fortnite frontier this week - Space.com

When life events knock you down, looking to the stars may give you a new perspective. It reminds you how small we are and how easy it is to find a diversion with your old friend, the camera.

It doesnt take a lot of expensive equipment to take good photos of the heavens. Astrophotography can involve equipment as simple as a DSLR (digital single-lens reflex) camera with an ISO (International Organization for Standardization) rating of at least 1600 (the higher the number, the more sensitive to light it is).

Besides the camera, your equipment should include a sturdy tripod and a lens with an aperture (f-stop) opening of f/2.8 or higher.. The lower the f-stop the more light flows into the camera.

The size of the lens is also important. If you want a wide view with lots of foreground and more sky you should choose a 14 mm, 16 mm, 20 mm or 35 mm lens. If you want to take pictures of the moon, you will need a lens in the range of 200 mm to 600 mm.

Now find your location and attach your camera to the tripod. Switch off your automatic settings and find either the bulb or manual setting, which allows you to leave open the shutter for long exposures. The manual setting on most cameras will allow exposures of up to 30 seconds. Adjust your aperture to the maximum opening (the smaller numbers). Also, turn off the autofocus feature.

This 20-second exposure at iso-800 shows the difficulty with residential light pollution.

(Mark Boster/Los Angeles Times)

Your training wheels are gone now that youve turned off the automatic settings, and you can begin to experiment with your cameras manual adjustments. Start by manually focusing your lens to infinity and setting the ISO to 1600.

If your camera allows, adjust your shutter speed for an exposure of 15 to 30 seconds. Remember that Earth is rotating, so stars can appear to be streaking with exposures of 30 seconds.

Adjust your cameras image quality setting to RAW mode, which enables the highest-quality picture. Processing the pictures in RAW mode using Adobe Photoshop, Adobe Lightroom or other post-production tools provides better color and contrast control.

There are apps for everything, including astrophotography. Raul Roa, an avid astrophotographer, suggests the Planets app, which gives precise locations and times for viewing Polaris, the Milky Way and other celestial objects. Roa also uses the Sun Surveyor app, which shows where and when the Milky Way will rise, which is useful in planning your trips or locations.

Stan Honda, another former news photographer-turned-astrophotographer, offers his favorite apps: SkySafari, PhotoPills and Stellarium, all of which give you an idea of what you can see right now.

Before heading out to photograph the night sky, check the Weather page in the Times or online for the phases of the moon. Look for when the moon will be full, when it rises and when it sets.

Roa likes chasing the moon, he said, because it is something primordial. I look up and just think of what or who might be out there. Most of us will never get a chance to step off the Earth, so looking up and dreaming is the next best thing for me.

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Astronomy tips: How to photograph the moon, stars, and sky - Los Angeles Times

There's an asteroid closing in on a safe Earth flyby. That's nothing unusual - near-Earth space has a lot of rocks in it. But 1998 OR2 is distinguishing itself in a series of happy snaps as it draws closer to periapsis.

Both the Virtual Telescope Project in Rome and the Arecibo Observatory in Puerto Rico have managed to catch glimpses of the asteroid as it grows brighter in our skies, travelling through space at around 31,320 kilometres per hour (19,461 miles per hour).

We have nothing to fear from 1998 OR2. It's relatively large, but it's not going to come close enough to threaten Earth. The asteroid was discovered in 1998, and astronomers have been watching it carefully to calculate its orbital path, which is projected all the way until the year 2197.

This year, 2020, will mark the asteroid's closest flyby in at least a century, and it's going to sail harmlessly past at a distance of 6.3 million kilometres (around 4 million miles). That's over 16 times the average distance between Earth and the Moon.

But because it's so large - estimates put it at around 4.1 kilometres long and 1.8 kilometres wide (2.5 by 1.1 miles) - it's unusually bright. It's therefore one of the largest and brightest near-Earth asteroids, and when it flies by on April 29 - periapsis, or its closest orbit, will be around 09:56 GMT - amateur astronomers may even be able to see it with smaller telescopes.

It is classed as a 'potentially hazardous' asteroid, because all asteroids above a certain size (140 metres) and within a certain distance of Earth (7,480,000 kilometres or 4,650,000 miles) are automatically classified as such.

But projections for 1998 OR2 don't indicate any kind of collision in our future. The next time it will come close to Earth will be in 2079, when it will swing by at a distance of 1.8 million kilometres (1.1 million miles). That's around 4.6 times the lunar distance.

In fact, this flyby is really cool. It will allow astronomers to take measurements of the asteroid so we can refine our size estimation techniques. We can also study the asteroid itself, to learn more about the composition of these space rocks. And tracking these objects also helps us develop measures for defending Earth against asteroids that could be genuinely hazardous.

If you want to try to catch a glimpse of this awesome chunk of rock, EarthSky has detailed instructions on the equipment you will need, and where in the sky to look.

If you are in the wrong place, or don't have a telescope, though, never fear - the Virtual Telescope Project will be livestreaming the event on its website.

See more here:

Astronomers Took New Pics of 1998 OR2, The Asteroid About to Whoosh Past Earth - ScienceAlert

In another first, scientists at the LIGO and Virgo gravitational wave detectors announced a signal unlike anything theyve ever seen before. While many black hole mergers have been detected thanks to LIGO and Virgos international network for detectors, this particular signal (GW190412) was the first where the two black holes had distinctly different masses.

The event was observed by both LIGO and Virgo on April 12th, 2019, early in the detectors third observation run (O3). According to the study that describes the find, which recently appeared online and the LIGO website, GW190412 took place about 1.9 to 2.9 billion light-years from Earth. It involved the merger of two black holes weighting approximately 8 and 30 Solar masses, respectively.

The event is unique in the history of gravitational wave astronomy since all binaries observed previously by the LIGO and Virgo detectors consisted of two roughly similar masses. Analyses revealthat the merger happened at a distance of 1.9 to 2.9 billion light-years from Earth. The new unequal mass system is a unique discovery since all binaries observed previously by the LIGO and Virgo detectors consisted of two roughly similar masses.

This sharp difference in mass allowed the LIGO/Virgo scientists to verify something predicted by Einsteins General Theory of Relativity, which has so far remained untested. Frank Ohme is the leader of the Independent Max Planck Research Group aka. the Binary Merger Observations and Numerical Relativity at the Albert Einstein Institute (AEI). As he stated in a recent AEI press release:

For the very first time we have heard in GW190412 the unmistakable gravitational-wave hum of a higher harmonic, similar to overtones of musical instruments. In systems with unequal masses like GW190412 our first observation of this type these overtones in the gravitational-wave signal are much louder than in our usual observations. This is why we couldnt hear them before, but in GW190412, we finally can.

These observations once again confirms the theory of General Relativity (GR), which states that massive objects alter the curvature of space time and cause ripples aka. gravitational waves when they merge. The theory also predicts that binary systems where two objects are vastly different in terms of mass will introduce higher harmonics into the waveform.

When the LIGO and Virgo collaborations examined the signal produced by GW190412, they observed this very phenomenon at work for the first time in history. In short, the fundamental frequency of the GWs were two or three times higher than what has been observed with all other events that have been detected so far.

Says Roberto Cotesta, a PhD student in the Astrophysical and Cosmological Relativity division at the AEI in Potsdam:

The black holes at the heart of GW190412 have 8 and 30 times the mass of our Sun, respectively. This is the first binary black-hole system we have observed for which the difference between the masses of the two black holes is so large! This big mass difference means that we can more precisely measure several properties of the system: its distance to us, the angle we look at it, and how fast the heavy black hole spins around its axis.

Another benefit of this latest detection is that it allowed the team to measure the systems astrophysical properties with greater precision. In short, unequal masses imprint themselves on a GW signal, which in turn allows scientists to more precisely measure properties like the mass and spin of the merging objects, as well as the distance to the source and angle of observation.

Essential to this was the accurate models of GWs produced from coalescing black holes, which were provided by researchers from the Albert Einstein Institute. For the first time, these models included both the precession of the black-holes spins and multipole moments beyond the dominant quadrupole which were crucial to measuring their properties and carrying out tests of GR.

The Institutes high-performance Minerva and Hypatia computer clusters at AEI Potsdam and Holodeck at AEI Hannover also played a significant role in the analysis of the signal. According to Alessandra Buonanno, the director of the Astrophysical and Cosmological Relativity division at the AEI, this type of unique signal is something that the two previous observations runs failed to detect. As she said:

During O1 and O2, we have observed the tip of the iceberg of the binary population composed of stellar-mass black holes. Thanks to the improved sensitivity, GW190412 has begun to reveal us a more diverse, submerged population, characterized by mass asymmetry as large as 4 and black holes spinning at about 40% the possible maximum value allowed by general relativity.

Another reason why this kind of observation was not possible before has to do with the recent upgrades made at all the detectors in the LIGO/Virgo international network. This includes a new technique where the quantum-mechanical properties of the lasers used by LIGO and Vigro are squeezed to enhance the sensitivity of the detectors.

This technique was pioneered by researchers at the German-British GEO600 detector in South Hanover, Germany designed and operated by scientists from the Max Planck Institute and multiple European universities. The technique has improved the sensitivity of the GEO600 detector by a factor of two and the AEI is leading the global effort to maximize the effectiveness of the light squeezing technique further.

When the first GW event was detected by scientists at LIGO in February of 2016, it signaled a new age in astronomy. In just over four years, improvements made to individual detectors and international collaborations have ushered in an era where events are being detected every week.

With every new detection, we are learning more about the exotic physics that power our Universe. Be sure to check out this simulation of what the GW190412 merger looked like, courtesy of the Albert Einstein Institute:

Further Reading: Albert Einstein Institute, LSC

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Astronomers Detected a Black Hole Merger With Very Different Mass Objects - Universe Today

This is a piece of the puzzle that gets stacked on top of other points below. Do you need a telescope to start stargazing? Not necessarily. Though you can't see everything with the naked eye. So, it depends on what you're looking for. If you want to view deep-space objects, youre going to need a telescope. If youre looking at planets, youll be able to see a lot of them with the naked eye. Venus, Mars, Saturn, and Jupiter are all easily visible. However, even a pair of binoculars will give you a more impressive view.

However, there are tools available beyond telescopes and binoculars. "The first thing I did when I started is to subscribe to the national magazines," Sreenivasan said. "The two largest ones are Sky and Telescopeand Astronomy." Though, he notes you can read them online as well. They have details about what you can see in the night sky over the coming weeks. (Of course, Thrillist also has details on many space events throughout the year.)

Additionally, there are apps that use augmented reality to show you what's in the sky and help you track down objects you want to see. Some of the most popular apps include Sky View, Sky Safari, Star Walk, and Night Sky. "Also, invest in a star atlas," Sreenivasan said. "There are several out there like Sky & Telescopes Pocket Sky Atlas.Thats one a lot of beginners use, and I still use it myself when I travel. Its just a set of star maps. Its a pretty small book, but its a pretty good book."

Continue reading here:

Everything You Need to Know to Take up Stargazing - Thrillist

Thursday, 23 April 2020, 2:44 pmPress Release: University of Canterbury

University of Canterbury (UC) astronomers arepart of an international team that has revealed howexplosions on the surface of a white dwarf star can increaseits brightness by thousands or millions of times making itlook like a new star.

For many yearsastronomers have thought that nuclear fusion of material onthe surface of a white dwarf directly powers all the lightfrom a nova explosion, which happen about 10 times a year inour galaxy.

A nova, or stella nova Latin fornew star is a sudden explosion on the surface of awhite dwarf, which is the hot, burnt-out core of a star. Itproduces an incredible amount of energy and light,increasing the stars brightness by thousands or evenmillions of times. If a nova occurs relatively close toearth it can appear as a new star to the naked eye.

Innew research, a team of international astronomers has shownthat shock waves from the nova explosion, rather thannuclear fusion, cause most of the brightness.

The teamused NASAs space-based telescopes and ground-basedtelescopes, including some at the UCMt John Observatory in Tekapo, to observe a recentnearby nova in the constellation of Carina and proved thatit is indeed shock waves that cause most of the novasbrightness.

Their results are documented in a newpaper called Direct evidence for shock-powered opticalemission in a nova published this month in theinternational journal NatureAstronomy.

UC Associate Professor in Astronomyand Director of the University of Canterbury Mt JohnObservatory KarenPollard, who co-authored the paper, was observing atUCs Mt John Observatory using the McLellan telescope andHERCULES spectrograph a few days after the bright nova inCarina was reported.

I was excited to observe it a new bright novae in the galaxy is an importantopportunity to make a detailed study of the novasproperties and how these change with time. Usingspectroscopy we were able to examine shock-produced emissionand calculate how energetic the shock waves were and howfast the shocked material was moving, shesays.

Elias Aydi, a research associate in MichiganState Universitys (MSU) Department of Physics andAstronomy and lead author of the paper, says the discoveryleads to a new way of understanding the origin of thebrightness of novae and other stellar explosions. Ourfindings present the first direct observational evidence,from unprecedented space observations, that shocks play amajor role in powering these events.

When materialblasts out from the white dwarf, he says it is ejected inmultiple phases and at different speeds. These ejectionscollide with one another and create shocks, which heat theejected material producing much of the light.

Anotherside effect of astronomical shocks are gamma-rays, thehighest-energy kind of electromagnetic radiation. Theastronomers detected bright gamma-rays from the star, knownas nova V906 Carinae (ASASSN-18fv), whose explosion in theconstellation Carina was first detected in March2018.

An optical satellite happened to be looking atthe part of the sky where the nova occurred. Comparing thegamma-ray and optical data, the astronomers noted that everytime there was a fluctuation in gamma-rays, the light fromthe nova fluctuated as well.

The simultaneousfluctuations in both the visual and gamma-ray brightnessconfirmed that both were originating from shocks.

Theresearch team estimates that V906 Car is about 13,000 lightyears from Earth. This means that when the nova was firstdetected in 2018, it had actually happened 13,000 years ago.The new information may also help explain how large amountsof light are generated in other stellar events, includingsupernovae and stellar mergers, when two stars collide withone another. Each nova explosion releases about 10,000 to100,000 times the annual energy output of theSun.

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Astronomers Discover The Science Behind Star Bursts That Light Up The Sky - Scoop.co.nz