Are you ready for the new kid on the block? Its name is Comet Yi-SWAN and it’s not going to be very long before it’s easily within range of small telescopes and larger binoculars. So where is it at? Head out to the early morning skies for your best look, because it’s rockin’ with the Queen – Cassiopeia.
Discovered photographically by Korean amateur astronomer, Dae-am Yi, on March 26th – word didn’t reach the Central Bureau for Astronomical Telegrams (CBAT) at the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts until after it had been independently picked up on SWAN images by professional astronomer, Rob Matson, on April 4. (Now why doesn’t that surprise me?) However, once CBAT astronomers realized that both reports were for the same object, it officially took on the name Comet Yi-SWAN (C/2009 F6).
Right now the new comet is traveling in a highly inclined parabolic orbit, moving slowly across the constellation of Cassiopeia toward Perseus. While Comet Yi-SWAN is currently only a few arc minutes in size and averaging about 8.5 magnitude, it’s going to be very difficult to spot because of the moonlight. However, if you’re interested in catching the latest visitor from the Oort cloud, you just might want to try on Saturday evening, April 11 when Yi-SWAN will be located less than half a degree south of Alpha Cassiopeiae. If you’re clouded out? Try again on Thursday, April 23-24 when it will pass south of NGC 884 and NGC 869 (the “Double Cluster”).
Happy Hunting!!
NASA image on this page is archival and does NOT represent Comet Yi-SWAN or its position. It is strictly for illustratory purposes.
It was an energetic event that occurred over Tunguska, but what caused it? (Don Davis)
[/caption]Over a century ago, on June 30th, 1908 a huge explosion detonated over an unpopulated region of Russia called Tunguska. It is probably one of the most enduring mysteries of this planet. What could cause such a huge explosion in the atmosphere, with the energy of a thousand Hiroshima atomic bombs, flattening a forest the area of Luxembourg and yet leaving no crater? It is little wonder that the Tunguska event has become great material for science fiction writers; how could such a huge blast, that shook the Earth’s magnetic field and lit up the Northern Hemisphere skies for three days leave no crater and just a bunch of flattened, scorched trees?
Although there are many theories as to how the Tunguska event may have unfolded, scientists are still divided over what kind of object could have hit the Earth from space. Now a Russian scientist believes he has uncovered the best answer yet. The Earth was glanced by a large comet, that skipped off the upper atmosphere, dropping a chunk of comet material as it did so. As the comet chunk heated up as it dropped through the atmosphere, the material, packed with volatile chemicals, exploded as the biggest chemical explosion mankind had ever seen…
12,000 years ago, a large object smashed into North America, causing global destruction. Dust and ash was released into the atmosphere, triggering global cooling and possibly causing the extinction of a number of large mammals around this time. The Tunguska event was of a similar energy to that catastrophic impact, but fortunately for us, Tunguska had a benign effect on the world. It simply exploded high in the atmosphere, flattened a region of Russia and vaporized.
“Significantly, the energy of the chemical explosion is substantially lower than the kinetic energy of the body,” says Edward Drobyshevski of the Russian Academy of Sciences in St Petersburg, who has published his research into the Tunguska event. The fact that the Tunguska explosion energy is lower than what is expected of the kinetic energy of an object that hit the Earth from space is key to his work. Drobyshevski therefore concludes that the event must have been caused not by an asteroid or whole comet, it was actually caused by a fragment of comet material that fell off as the main cometary body skipped off the Earth’s upper atmosphere. This means that the Earth was hit on a tangent and the fragment dropped comparatively slowly toward the surface.
Sounds reasonable so far, but how did the fragment explode? Using our new understanding as to what chemicals comets contain, Drobyshevski surmises the fragment was rich in hydrogen peroxide. This is where the magic happened. The explosion was not due to a rapid release of kinetic energy, it was in fact a hydrogen peroxide bomb. As the fragment descended, it heated up. As the reactive chemicals in the material got hot, they explosively disassociated to form oxygen and water, ripping the fragment apart. The Tunguska event was therefore a huge chemical bomb and not a “regular” comet-hits-Earth impact.
An interesting study. Not content with dropping asteroids on our planet, the Universe has started throwing hydrogen peroxide explosives at us too. Whatever next?
Comet Lulin and Saturn in Parallel Vision by Jukka Metsavainio
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Have you ever wondered what it would be like to step into space and have a look at solar system objects in aspect? While we can view interesting and inspiring events like Comet Lulin’s recent conjunction with Saturn, what we can’t quite get our brains to wrap around it how it would appear in dimension. Thanks to some “magic” by Jukka Metsavainio and some of his own outstanding astrophotography – now we can…
Like all our our “stereo” image produced for UT by Jukka Metsavainio, two versions are presented here. The one above is parallel vision – where you relax your eyes and when you are a certain distance from the monitor screen the two images will merge into one to produce a 3D version. The second – which appears below – is crossed vision. This is for those who have better success crossing their eyes to form a third, central image where the dimensional effect occurs. In this case, Jukka had the opportunity to photograph Comet Lulin during its recent conjuntion with Saturn and he was willing to share the view in a visualization of how the pair would have appeared in binoviewers – or if you were able to see them with both eyes from space! Ready to get crossed? Then let’s go….
Comet Lulin and Saturn in Cross Vision by Jukka Metsavainio
After having just viewed Comet Lulin a few hours before seeing this image, I knew I just had to share. Thanks to the comet’s unique position along our ecliptic plane, the pleasure of catching it in the eyepiece with other telescopic objects isn’t over yet. For observers in the United States, on March 6, this Thursday evening, Comet Lulin will pass 2 degrees south of the Beehive Star Cluster, M44. On Saturday, March 14, Lulin will pass only 15 arc minutes (half the moon’s apparent diameter) away from the Eskimo Nebula, NGC 2392. But don’t think you have to live in the US to see it!
As with all conjunction events, your position and timing on Earth will play an important role on where the comet will appear in relation to the object. For example, for observers in the UK, Lulin may be to M44’s southeast – while the west coast of Canada will see it to the southwest. The same is true of latitude as well – your variation here on Earth will give an equal variation on Comet Lulin’s positon against the celestial sphere. But, don’t go crazy trying to worry about its exact position. Two degrees is a lot of sky and chances are no matter when you view on March 6, you’ll catch it in (or near) the same binocular field as the Beehive.
In the meantime? Enjoy this incredible look at Comet Lulin and Saturn… It’s a tasty treat!
Roughly 38 million miles from Earth and traveling at a relative velocity of 140,000 miles per hour, the speedy Comet C/2007 N3 Lulin has caught our imaginations in a big way during the beginning months of the International Year of Astronomy. Right now, Comet Lulin has already sped past the Sun, slipped by stately Saturn from our point of view and is on a parabolic trajectory heading out from our solar system. This means it will never come back… Continue reading “Comet Lulin Video – Watch the Outgassing Process”
Comet Lulin on Feb. 22, taken by John Nassr, Baguio, Philippines, via Spaceweather.com
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We’ve received a few emails asking for more information about how to attempt to observe Comet Lulin. And Sky and Telescope has put out a great primer for seeing this green smudgeball in North America. Right now is the optimum time to try and see it. Sky and Telescope editor-in-chief Robert Naeye says Lulin should be at its best from Feb. 23 through the 28th. “In a very dark, unpolluted, natural night sky — such as few people see any more — the comet is dimly visible to the unaided eye,” writes Naeye. “Even in a more light-polluted suburban sky, however, a good pair of binoculars will do the trick. But you have to know exactly where to look.”
Start looking for Lulin after 9:00 pm (your local time) but the view will be better after 10:00 pm.
“It shows the starry view high in the east-southeast in mid-evening. You should have no trouble spotting the planet Saturn and the star Regulus in the constellation Leo. They’re the two brightest things in the area.
“Using those as your guide, aim at the point on the comet’s path that’s labeled with the current date. The comet’s position is indicated for the evening hours on each date for the time zones of the Americas. The orientation of the scene with respect to the horizon is drawn for North America.
“You’re looking for a very dim, biggish, slightly oval cotton-puff floating among the tiny pinpoint stars. Look carefully, and you may detect the spike of the comet’s “anti-tail” pointing toward the lower left. The comet’s regular tail is actually dimmer, and it points in almost the opposite direction. In binoculars the whole thing looks more gray than greenish; to see color you need more light. In a large amateur telescope, the color and the comet’s structure are a lot more clearly visible.
“I saw it out my bathroom window with 10-by-50 binoculars,” says Alan MacRobert, a senior editor of Sky & Telescope. “It’s pretty plain if you get aimed at exactly the right spot.”
This image of Comet Lulin taken Jan. 28 merges data acquired by Swift's Ultraviolet/Optical Telescope (blue and green) and X-Ray Telescope (red). At the time of the observation, the comet was 99.5 million miles from Earth and 115.3 million miles from the sun. Credit: NASA/Swift/Univ. of Leicester/Bodewits et al.
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The Swift spacecraft is doing double duty these days. Normally, the Gamma-ray Explorer satellite is on the lookout for high-energy outbursts and cosmic explosions. But now Swift is also monitoring Comet Lulin as it comes closer to Earth. For the first time, astronomers are seeing simultaneous ultraviolet and X-ray images of a comet. “The comet is releasing a great amount of gas, which makes it an ideal target for X-ray observations,” said Andrew Read, also at Leicester. And the ultraviolet data shows that Lulin is also shedding a huge amount of water, about 800 gallons of water each second!
“We won’t be able to send a space probe to Comet Lulin, but Swift is giving us some of the information we would get from just such a mission,” said Jenny Carter, at the University of Leicester, U.K., who is leading the study.
Comets are called “dirty snowballs,” as they are clumps of frozen gases mixed with dust. As comets venture near the sun, gas and dust are released. Comet Lulin, which is formally known as C/2007 N3, was discovered last year by astronomers at Taiwan’s Lulin Observatory. The comet is now faintly visible from a dark site. Lulin will pass closest to Earth — 38 million miles, or about 160 times farther than the moon — late on the evening of Feb. 23 for North America.
On Jan. 28, Swift trained its Ultraviolet/Optical Telescope (UVOT) and X-Ray Telescope (XRT) on Comet Lulin. “The comet is quite active,” said team member Dennis Bodewits, a NASA Postdoctoral Fellow at the Goddard Space Flight Center in Greenbelt, Md. “The UVOT data show that Lulin was shedding nearly 800 gallons of water each second.” That’s enough to fill an Olympic-size swimming pool in less than 15 minutes. Comet Lulin was passing through the constellation Libra when Swift imaged it. This view merges the Swift data with a Digital Sky Survey image of the star field. Credit: NASA/Swift/Univ. of Leicester/DSS (STScI, AURUA)/Bodewits et al.
Swift can’t see water directly. But ultraviolet light from the sun quickly breaks apart water molecules into hydrogen atoms and hydroxyl (OH) molecules. Swift’s UVOT detects the hydroxyl molecules, and its images of Lulin reveal a hydroxyl cloud spanning nearly 250,000 miles, or slightly greater than the distance between Earth and the moon.
The UVOT includes a prism-like device called a grism, which separates incoming light by wavelength. The grism’s range includes wavelengths in which the hydroxyl molecule is most active. “This gives us a unique view into the types and quantities of gas a comet produces, which gives us clues about the origin of comets and the solar system,” Bodewits explains. Swift is currently the only space observatory covering this wavelength range.
In the Swift images, the comet’s tail extends off to the right. Solar radiation pushes icy grains away from the comet. As the grains gradually evaporate, they create a thin hydroxyl tail.
Farther from the comet, even the hydroxyl molecule succumbs to solar ultraviolet radiation. It breaks into its constituent oxygen and hydrogen atoms. “The solar wind — a fast-moving stream of particles from the sun — interacts with the comet’s broader cloud of atoms. This causes the solar wind to light up with X rays, and that’s what Swift’s XRT sees,” said Stefan Immler, also at Goddard.
This interaction, called charge exchange, results in X-rays from most comets when they pass within about three times Earth’s distance from the sun. Because Lulin is so active, its atomic cloud is especially dense. As a result, the X-ray-emitting region extends far sunward of the comet.
“We are looking forward to future observations of Comet Lulin, when we hope to get better X-ray data to help us determine its makeup,” noted Carter. “They will allow us to build up a more complete 3-D picture of the comet during its flight through the solar system.”
The Bejar bolide photographed from Torrelodones, Madrid, Spain. The incoming fireball is the streak to the right of the floodlit house. The bright light at the top is the overexposed Moon. Credit: J. Perez Vallejo/SPMN.
Astronomers have analyzed the cometary fireball that blazed across the sky over Europe last year and concluded it was a dense object, about a meter (3.2 feet) across and with a mass of nearly two tons — large enough that some fragments probably survived intact and fell to the ground as meteorites.
Last July, people in Spain, Portugal and France watched the brilliant fireball produced by a boulder crashing down through the Earth’s atmosphere. In a paper to be published in the journal Monthly Notices of the Royal Astronomical Society, astronomer Josep M. Trigo-Rodríguez, of the Institute of Space Sciences in Spain, and his co-authors present dramatic images of the event. The scientists also explain how the boulder may originate from a comet which broke up nearly 90 years ago, and suggest that chunks of the boulder (and hence pieces of the comet) are waiting to be found on the ground.
“If we are right, then by monitoring future encounters with other clouds of cometary debris, we have the chance to recover meteorites from specific comets and analyse them in a lab,” Dr Trigo-Rodríguez said. “Handling pieces of comet would fulfil the long-held ambitions of scientists — it would effectively give us a look inside some of the most enigmatic objects in the Solar System.”
Fireballs (or bolides) are the name given by astronomers to the brightest meteors, popularly referred to as shooting stars. On the afternoon of July 11, a brilliant fireball was recorded over southwestern Europe. At maximum intensity, the object was more than 150 times brighter than the full Moon. It was first picked up at a height of 61 miles (98.3 km) and disappeared from view 13 miles (21.5 km) above the surface of the Earth, tracked by three stations of the Spanish Fireball Network above Bejar, near Salamanca in Spain. At the same time, a professional photographer took a picture of the fireball from the north of Madrid.
A close-up image of the Bejar bolide, photographed from Torrelodones, Madrid, Spain. Credit: J. Perez Vallejo/SPMN.
From these images, the astronomers have demonstrated that before its fiery demise, the boulder traveled on an unusual orbit around the Sun, which took it from beyond the orbit of Jupiter to the vicinity of Earth. This orbit is very similar to that of a cloud of meteoroids known as the Omicron Draconids, which on rare occasions produces a minor meteor shower and probably originates from the breakup of Comet C/1919 Q2 Metcalf in 1920. The authors suggest the boulder was once embedded in the nucleus of that comet.
Comet C/1919 Q2 Metcalf was discovered by Joel Metcalf from Vermont in August 1919, and was visible until February 3, 1920. The orbit was not well determined and no subsequent appearances are known. The Omicron Draconids meteor stream was discovered to be following a similar orbit to this comet by Allan F. Cook in 1973. The stream characteristically produces bright fireballs and rare meteor outbursts.
In the mid-1980s, the astronomers Tamas I. Gombosi and Harry L.F. Houpis first suggested that the nuclei of comets consist of relatively large boulders cemented together by a ‘glue’ of smaller particles and ice. If the rocky and icy nucleus of a comet disintegrates, then these large boulders are set loose into space. If the Bejar bolide was formed in this way, it confirms the glue model for at least some comets.
When Chi-Sheng Lin of Taiwan’s Institute of Astronomy captured three images on July 11, 2007 with something strange in them, it was first believed he’d picked up just another asteroid. But, by July 17 astronomers in Table Mountain Observatory, California were noticing a coma 2-3″ across, with a bright central core. That’s not an asteroid… That’s a comet! And now it’s a comet that’s doing something very strange…
By the end of 2008, Comet C/2007 N3 Lulin had steadily began to brighten and now is within easy reach of binoculars for all observers. How bright is it? At last estimate it is between magnitude 6 and 7. That means just a little too faint to be seen unaided, but bright enough to be spotted easily with just the slightest of visual aids. Our own Nancy A. did an article on this not long ago!
But there’s something going on with N3 Lulin, right now… Something very different. There’s a twist in the tail! Check this out…
Comet C/2007 N3 Lulin (negative luminance) - J. Brimacombe
While imaging N3 Lulin for UT Readers, Dr. Joe Brimacombe used a negative luminance frame to take a closer look at what’s going on and discovered something quite out of the ordinary. First off, you’ll notice an anti-tail – quite rare in itself – but if you take a look about halfway down the ion/dust tail, you’ll see a very definite twist in the structure. It it rotating? Exactly what’s causing it? Torsional stress? Is it possible that the kink in the tail is an instability resulting from currents flowing along the tail axis? Right now there’s absolutely no information available about what’s going on in the tail – because what you’re seeing is perhaps one of the most current pictures of the comet that can be found!
Chart Courtesy Heaven's AboveIf you’re interested in viewing Comet C/2007 N3 Lulin for yourself and would like some help locating it, there’s a wonderful resource that’s easy to use. Just go to Chris Peet’s Heaven’s Above website and make use of the tools there. It will give you easy to follow charts and all you need is just a pair of binoculars to spot this comet for yourself. Don’t sit inside… Do it!
My sincere thanks to Dr. Joseph Brimacombe of Northern Galactic for not only his superb imaging – but his sublime sense of curiosity which caught this anomaly!
Comet Lulin on January 11, 2009. Credit: Gregg Ruppel
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A new comet is swinging around the sun, and soon it will be more visible to stargazers, perhaps even with the naked eye. Both professional and amateur astronomers have been tracking this unusual comet, named Comet Lulin. Thanks to amateur astronomer Gregg Ruppel, who lives in the St. Louis, Missouri area for sharing images he has acquired of Comet Lulin. Gregg took the image above on January 11, 2009. The most interesting characteristic of this comet is its orbit. Lulin is actually moving in the opposite direction as the planets, so its apparent velocity will be quite fast. Estimates are it will be moving about 5 degrees a day across the sky, so when viewed with a telescope or binoculars, you may be able to see the comet’s apparent motion against the background stars. This is quite unusual! Today, January 14, the comet is at perihelion, closest to the sun. As it moves to its closest approach to Earth on February 24, Lulin is expected to brighten to naked-eye visibility in rural areas, (at best about magnitude 5 or 6) and will be observable low in the sky in an east-southeast direction before dawn.
Comet Lulin on January 8, 2009. Credit: Gregg Ruppel
The comet will pass 0.41 Astronomical Units from earth at its closest distance to Earth, about 14.5 times the distance between the Earth and the Moon. It has a parabolic trajectory, which means it may have never come this way before –this may be its first visit to the inner solar system
Lulin was jointly discovered by Asian astronomers in July of 2007. Quanzhi Ye from China first saw the comet on images obtained by Chi-Sheng Lin from Taiwan, at the Lu-lin Observatory.
The discovery of Comet Lulin (also known as C/2227 2007 N3) was part of the Lulin Sky Survey project to explore the various populations of small bodies in the solar system, especially objects that could be a hazard to the Earth.
It has both a tail and an anti-tail, visible in this image. Lulin's Tails. Credit: Gregg Ruppel.
Artist rendering of Stardust-NeXT spacecraft approaching Earth's gravitational pull, resulting in accelerating of spacecraft and bending of flight path. Courtesy: NASA
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Remember the Stardust mission that returned samples of comet dust back to Earth in 2006? The spacecraft dropped off a capsule containing samples of a comet’s coma and interstellar dust particles, but the spacecraft “bus” is still out there in an elongated orbit of the sun. It will come home again, swinging by Earth on January 14, at 19:40 UTC (12:40 pm PST), getting a gravity assist from the home planet as it flies approximately 5713 miles (9200 kilometers) from the Earth’s surface. But the spacecraft isn’t just wandering the solar system with nothing to do. It has a new job and a new mission. Called Stardust NExT, (New Exploration of Tempel 1) the spacecraft will re-survey comet Tempel 1 – the comet that the Deep Impact mission left a mark on — encountering the comet on Feb. 14, 2011.
And remember aerogel – the wispy material that collected the comet dust? Turns out this stuff can come home, too: into homes and other buildings as a super-insulating material. Engineers say using aerogel as an insulator can increase the thermal insulation factor of a wall by over 40%!
Lightweight, wispy aerogel. Credit: NASA
If you’ve ever had the chance to handle aerogel, you know it’s really weird stuff. It’s fragile, but it’s also strong. You can crush it easily in your hand, but it has just the right qualities to be able to capture dust particles zooming in space at extremely high speeds without breaking, and was “gentle” enough to preserve the particles. Engineers say the aerogel insulation technology developed by NASA, is the highest insulating material in existence, and the company Thermablok(TM) developed an amazing product that may soon become a requirement in the building industry.
Aerogel, also referred to as “frozen smoke,” has been difficult to adapt to most uses because it’s so fragile The patented Thermablok material however overcomes this by using a unique fiber to suspend a proprietary formula of Aerogel such that it can be bent or compressed while still retaining its amazing insulation properties. Aerogel-based insulation.
Aerogel material is 95% air, and just a 1/4″ x 1-1/2″ (6.25mm x 38mm) strip of Thermablok(TM) added to each stud in a wall before putting on drywall, breaks the “thermal bridging,” increasing the thermal insulation factor of a wall by 42%.
The U.S. Department of Energy has verified the findings on the producst’s thermal capability. Plus its recyclable, fire resistant and not affected by water (so no mold).
Speaking of recyclable, NASA’s plans for the Stardust spacecraft to revisit Tempel 1 will finish the investigation begun in 2005 when the Deep Impact mission blasted a crater into the comet. “The crater’s there,” said Joseph Veverka, Professor of Astronomy at Cornell University and Principal Investigator of Stardust-NExT, “but we’ve never seen it.” That’s because the cloud of material ejected from the crater obscured the Deep Impact spacecraft’s view. By the time the particles slowly settled back down to the comet’s surface, the spacecraft, traveling at about 10 km (about 6 miles) per second, was gone.
Looking into the crater with Stardust-NExT will provide mankind’s first view of a comet’s internal structure, information that is not only scientifically interesting, but vital to our future ability to keep a comet from hitting the Earth. Even the size of the crater will be revealing. “That will tell us the mechanical properties of the subsurface of the comet,” Veverka said. “In other words, how does the comet respond to impacts? And that’s one of the fundamental things that you’d need to know if you were trying to blow up a comet or push it out of the way.”
Stardust was originally launched in 1999, and in January 2004, the spacecraft performed a risky and historic flyby of Comet Wild 2 to capture the samples and take pictures of the comet’s nucleus.
