Posted on by Nancy Atkinson

Guest Post: Comet Kerfuffle

An image generated from Starry Night software of how Comet ISON may look on November 22, 2013 from the UK.

Editor’s note: This guest post was written by Stuart Atkinson, a space and astronomy enthusiast who blogs at Cumbrian Sky, Road to Endeavour, which follows the Opportunity rover, and The Gale Gazette which discusses imagery from the Curiosity rover.

Unless you’ve been cut off from the internet today you’ll have heard about The Comet. No, not Comet PANSTARRS, which is due to shine in the sky next March, perhaps rivalling the fondly-remembered Comet Hale Bopp from 1996, but another comet. Comet 2012/S1, or “Comet ISON” to give it its full name. It’s everywhere you look on Twitter, Facebook, Google Plus. Why? Because initial calculations of its orbit show it will pass ridiculously close to the Sun next November, skimming the solar surface at a height of just under two million kilometres. And that means it might shine jaw-droppingly bright in the sky at that time, before it heads back off into deep space again.

So, of course, adding two and two to get fifty, there are lots of people getting more excited about this comet than a dog in a lamp post factory. If you were to believe some of the comments being written about it, it is absolutely nailed-on guaranteed to shine like a welding torch in the sky next November, blazing at magnitude -16, with a tail stretching across the sky like a WW2 searchbeam.

Can we all just calm down, please?

Although Comet ISON looks promising, very promising in fact, it’s very early days. It needs to be observed a lot more before we know exactly what’s in store for us, and even then what it will actually look like in the sky is impossible to predict this far ahead. You see, comets are notoriously unreliable, and love nothing better than getting astronomers on Earth all fired up with the promise of a dazzling nocturnal display before fizzling out and being so faint they need binoculars to see them. Hardly surprising, seeing as comets are essentially great big chunks of dirty ice, and we only see them because they’re melting and falling to pieces as they race around the Sun. You can’t predict how that will work out now, can you?

There’s a whole spectrum of possibilities here. At one end of that spectrum, ISON will live up to the most breathless predictions and blaze in the sky like a science fiction movie special effect. Its tail will span half the sky, becoming visible as soon as the Sun has set, and we will stand on our hillsides and in our gardens looking at it and slowly shaking our heads in wonder before we remember we’ve actually got a camera set up, and start taking pictures of it.

At the other end of the spectrum, ISON will play us all for fools, and even before its close solar flyby it will break up without developing a searchbeam tail, and we’ll all stand on our hillsides and in our gardens looking at it through binoculars and shaking our fists at it angrily, cursing its icy crust.

I think we should cross our fingers for something between the two. We should hope that ISON stays in one piece, survives its close encounter with the Sun, and shines in the twilight sky next November like another Lovejoy or McNaught. I’ll be happy with that, to be honest. Because I’m a citizen of the northern hemisphere my only views of Lovejoy were on my computer monitor, as I drooled over the images of it taken by astronomers and skywatchers in Australia and New Zealand and across the southern hemisphere. I caught a fleeting glimpse of McNaught from here in Kendal – standing in the ruins of the castle that stands above my town, I saw the comet through binoculars through a brief gap in the clouds, as I stood in the rain – but again I ‘saw’ it online rather than with my own eyes, cursing (good naturedly) all those people south of the equator who were seeing the real thing shining in their sky…

An image generated from Starry Night software of how Comet ISON may look on November 29, 2013 from the UK.

(I have to be honest here: having missed the last two Great Comets because of my latitude, when I fired up STARRY NIGHT earlier today, and stepped forward in time to next November, I experienced a rather ungentlemanly “Ha! Our turn!” moment of pure smugness as I saw that ISON’s path will carry it through my sky..!)

The best thing we can do, seriously, is just cross our fingers. Hope for the best, but prepare for…something less than that.

And yet…

Comets are magical, aren’t they? They bring out the dreamer, the optimist and the romantic in all of us. And although I’m fighting it, my head is full of images as I write this, memories of the comets I have seen before, and wondering what ISON will bring. I remember my first sighting of Halley’s Comet, on Guy Fawkes Night 1985. It was just a smudge of a blur in my binoculars, as I stood on the sports playing field near my home, breathing in the smell of bonfires and fireworks in the darkness; I remember standing in the deep, dark Cumbrian countryside, in the gravelled gateway of a farm field, and tracing out the ridiculous extent of Comet Hyakyutake’s pale green tail across the star-spattered sky; and I remember standing in the centre of the ancient Castlerigg stone circle outside Kewsick and, in perfect silence, and feeling a real connection to the watching Comet Hale-Bopp shining above the fells, its twin tails looking like they had been sprayed across the heavens by some cosmic grafitti artist…

What memories will I have after Comet ISON has flown past the Sun, I wonder…

It’s tempting to look at the elements of this comet, and to simulate its apparition using planetarium software, and to get excited. But really, let’s take it easy. I mean, we’ve been here before. Some comets in the past have promised the Earth (mentioning no names… *cough* Kohoutek *cough* ) only to pass by without any real fanfare or fuss, leaving astronomers with a lot of egg on their faces.

So, everyone, take a deep breath, and look at the calendar. ISON is going to be in the sky next November. NEXT November. That’s over a year away. Anything could happen before then.

And yet…

By Stuart Atkinson

Posted on by Nancy Atkinson

New ‘Sun-Skirting’ Comet Could Provide Dazzling Display in 2013

2013 is looking to be a promising year for potential naked-eye comets, as a new comet has been discovered that will likely skirt close to the Sun, and could provide a stunning display late next year. The comet, named Comet C/2012 S1 (ISON), as it was discovered by a Russian team at the International Scientific Optical Network (ISON), is currently about the distance of Jupiter’s orbit. But it is projected to come within less than 2 million km from the Sun at perihelion by November 28, 2013. Ernesto Guido and Giovanni Sostero from the Remanzacco Observatory in Italy, along with their colleague Nick Howes from the UK have imaged the comet with the RAS telescope in New Mexico, and say, “According to its orbit, this comet might become a naked-eye object in the period November 2013 – January 2014. And it might reach a negative magnitude at the end of November 2013.”

This new comet joins Comet C/2011 L4 PanSTARRS, which is projected to come within 45 million kilometers (28 million miles) of the Sun on March 9, 2013, which is close enough for quite a bit of cometary ice to vaporize and form a bright coma and tail. Comet PanSTARRS will be visible at perihelion to southern hemisphere, while Comet ISON should be visible to mid-latitude northern hemisphere skywatchers, according to the Remanzacco team.

Orbit diagram from JPL’s Small Body Database of Comet ISON, as of Sept. 25, 2012. Credit: JPL

Right now, Comet ISON is at magnitude +18, and only larger telescopes can see it. How bright will the comet get, and could it even be visible during daytime? That’s the big question which only time will answer. Just 2 million km distant from the Sun is incredibly close, and if the comet stays intact, some estimates say it could reach a brilliant negative magnitude of between -11 and -16. Comparatively, the full Moon is about magnitude -12.7.

But this will happen only if the comet will stay together. Comets can be fairly unpredictable, and other comets that have come that close to the Sun — such as Comet Elenin in 2011, Comet LINEAR in 1999 and Comet Kohoutek in 1973 — failed to live up to expectations of brightness and visibility.

But other comets have survived, like Comet Lovejoy earlier this year, which came two times closer, and Comet McNaught in 2007 which became visible even in daylight when it reached magnitude -5.5. It was not as close to the Sun as Comet ISON will be, however, as McNaught was about 24 million km away.

The discovery of C/2012 S1 (ISON) was made by Vitali Nevski, of Vitebsk, Belarus, and Artyom Novichonok, of Kondopoga, Russia with a 0.4-meter reflecting telescope near Kislovodsk, Russia.

You can see the ephermides of the Comet ISON here, from the Minor Planet Center.

The a Remanzacco Observatory team has more images, including an animation of Comet ISON on their website.

You can see the full visibility calculations of Comet ISON done by Daniel Fischer here.

Posted on by Nancy Atkinson

Comet Pan-STARRS: How Bright Will it Get?

Comet PanSTARRS on September 4, 2012 as seen from Puerto Rico. Credit: Efrain Morales/Jaicoa Observatory.

Early next year, a comet will come fairly close to Earth and the Sun — traveling within the orbit of Mercury — and it has the potential to be visible to the naked eye. Amateur and professional astronomers alike have been keeping watch on Comet C/2011 L4 PanSTARRS (or PanSTARRS for short), trying to ascertain just how bright this comet may become. It will come within 45 million kilometers (28 million miles) of the Sun on March 9, 2013, which is close enough for quite a bit of cometary ice to vaporize and form a bright coma and tail.

But just how bright, no one can say for sure. Comets have been known to be very unpredictable (remember the breakup of Comet Elenin?) but some estimates have said this comet could become a naked-eye object, as bright as Vega or Arcturus next March.

Right now it is at about Magnitude 12, and skywatchers in the southern hemisphere observers will have a great view as this comet gets closer and brighter, as it will remain high in the sky. But right now, skywatchers in the northern latitudes are saying farewell to Comet PANSTARRS, as it becomes low on the horizon. Astrophotographer Efrain Morales from Puerto Rico took the image above on September 4th, 2012 at 00:31 UTC. “It was very difficult to image due to the forest tree tops and sunset light but I was able to capture it at high magnification,” Efrain told us. (He used an LX200ACF 12 inch, OTA, CGE mount, F10, ST402xmi Ccd, Astronomik Ir/UV filter at 2 minutes. )

Observers in the mid-northern latitudes won’t be able to see the comet again until after its perihelion, unfortunately. And after that, we may never see Comet PanSTARRS again.

The discovery of the comet was made in June 2011 with the 1.8 meter (70.7 inch) Panoramic Survey Telescope & Rapid Response System or Pan-STARRS telescope on Mount Haleakala. PanSTARRS is looking to image the entire sky several times a month to hunt for Earth-approaching comets and asteroids that could pose a danger to our planet.

Richard Wainscoat and graduate student Marco Micheli confirmed the object was a comet using the Canada-France-Hawaii Telescope on Mauna Kea.

“The comet has an orbit that is close to parabolic,” Wainscoat said, “meaning that this may be the first time it will ever come close to the Sun, and that it may never return.”

Astronomers at the PanSTARRS telescope say that making brightness predictions for new comets is difficult because astronomers do not know how much ice they contain. Because sublimation of ice (conversion from solid to gas) is the source of cometary activity and a major contributor to a comet’s overall eventual brightness, this means that more accurate brightness predictions will not be possible until the comet becomes more active as it approaches the sun and astronomers get a better idea of how icy it is.

It will be an adventure to follow the comet’s close approach, and we hope our readers and astrophotographers in the southern hemisphere will keep us posted!

See our previous article about this comet.

Posted on by Nancy Atkinson

Asteroid Lutetia Flyby Animation

All asteroids and comets visited by spacecraft as of November 2010 Credits: Montage by Emily Lakdawalla. Ida, Dactyl, Braille, Annefrank, Gaspra, Borrelly: NASA / JPL / Ted Stryk. Steins: ESA / OSIRIS team. Eros: NASA / JHUAPL. Itokawa: ISAS / JAXA / Emily Lakdawalla. Mathilde: NASA / JHUAPL / Ted Stryk. Lutetia: ESA / OSIRIS team / Emily Lakdawalla. Halley: Russian Academy of Sciences / Ted Stryk. Tempel 1, Hartley 2: NASA / JPL / UMD. Wild 2: NASA / JPL.

In today’s Weekly Space Hangout, Emily Lakdawalla from the Planetary Society mentioned an animation of recently released images from the Rosetta mission’s flyby of asteroid Lutetia. It was put together and processed by Ian Regan, and Emily suggested you play this on a hand-held device (like a smart phone) in a dark room and move it around like you yourself are maneuvering the flyby! Try it — it is a very cool effect!

And while you’re at it, you also need to check out Emily’s montage poster of asteroids and comets, below:


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Check out more pretty images of Lutetia by Emily at the Planetary Blog.

Posted on by Nancy Atkinson

Frantic Comet Massacre Taking Place at Fomalhaut

Herschel's far-infrared observations of Fomalhaut and its disk. Credit: ESA

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There may be some frantic activity going on in the narrow, dusty disk surrounding a nearby star named Fomalhaut. Scientists have been trying to understand the makeup of the disk, and new observations by the Herschel Space Observatory reveals the disk may come from cometary collisions. But in order to create the amount of dust and debris seen around Fomalhaut, there would have to be collisions destroying thousands of icy comets every day.

“I was really surprised,” said Bram Acke, who led a team on the Herschel observations. “To me this was an extremely large number.”

Fomalhaut is a young star, just a few hundred million years old, about 25.1 light years away and twice as massive as the Sun. It is the brightest star in the constellation Piscis Austrinus and one of the brightest stars in our sky, visible in the southern sky in the northern hemisphere in fall and early winter evenings.

Fomalhaut’s toroidal dust belt was discovered in the 1980s by the IRAS satellite. It’s been viewed several times by the Hubble Space Telescope, but Herschel’s new images of the belt show it in much more detail at far-infrared wavelengths than ever before.

The narrow and asymmetrical properties of the disk are thought to be due to the gravity of a possible planet in orbit around the star, but the existence of the planet is still under study.

Hubble's view showing a possible exoplanet Fomalhaut b (NASA/HST)

Acke, from the University of Leuven in Belgium, and his team colleagues analyzed the Herschel observations and found the dust temperatures in the belt to be between –230 and –170 degrees C, and because Fomalhaut is slightly off-center and closer to the southern side of the belt, the southern side is warmer and brighter than the northern side.

Those observations collected starlight scattering off the grains in the belt and showed it to be very faint at Hubble’s visible wavelengths, suggesting that the dust particles are relatively large. But that appears to be incompatible with the temperature of the belt as measured by Herschel in the far-infrared.

While observations with Hubble suggested the grains in the dust disk would be relatively large, the Herschel data show that the dust in the belt has the thermal properties of small solid particles, with sizes of only a few millionths of a meter across. HST observations suggested solid grains more than ten times larger.

To resolve the paradox, Acke and colleagues suggest that the dust grains must be large fluffy aggregates, similar to dust particles released from comets in our own Solar System. These would have both the correct thermal and scattering properties.

However, this leads to another problem.

The bright starlight from Fomalhaut should blow small dust particles out of the belt very rapidly, yet such grains appear to remain abundant there.

So, the only way to explain the contradiction is to resupply the belt through continuous collisions between larger objects in orbit around Fomalhaut, creating new dust.

This isn’t the first time that evidence of cometary collisions have been seen around another star. Last year, astronomers using the Spitzer Space Telescope detected activity resembling a ‘heavy bombardment’ type of event where icy bodies from the outer solar system are possibly pummeling rocky worlds closer to the star.

At Fomalhaut, however, to sustain the belt, the rate of collisions must be remarkable: each day, the equivalent of either two 10 km-sized comets or 2,000 1 km-sized comets must be completely crushed into small, fluffy dust particles.

In order to keep the collision rate so high, scientists say there must be between 260 billion and 83 trillion comets in the belt, depending on their size. This is not unfathomable, the team says, as our own Solar System has a similar number of comets in its Oort Cloud, which formed from objects scattered from a disc surrounding the Sun when it was as young as Fomalhaut.

“These beautiful Herschel images have provided the crucial information needed to model the nature of the dust belt around Fomalhaut,” said Göran Pilbratt, ESA Herschel Project Scientist.

Source: ESA

Posted on by Nancy Atkinson

Getting a Handle on How Much Cosmic Dust Hits Earth

A starry sky, with a bright column due to zodiacal light, illuminates the desert landscape around Cerro Paranal, home to ESO's Very Large Telescope (VLT).

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Does Earth have a dust build-up problem?

Estimates vary of how much cosmic dust and meteorites enter Earth’s atmosphere each day, but range anywhere from 5 to 300 metric tons, with estimates made from satellite data and extrapolations of meteorite falls. Thing is, no one really knows for sure and so far there hasn’t been any real coordinated efforts to find out. But a new project proposal called Cosmic Dust in the Terrestrial Atmosphere (CODITA) would provide more accurate estimates of how much material hits Earth, as well as how it might affect the atmosphere.

“We have a conundrum – estimates of how much dust comes in vary by a factor of a hundred,” said John Plane from University of Leeds in the UK. “The aim of CODITA is to resolve this huge discrepancy.”

Even though we consider space to be empty, if all the material between the Sun and Jupiter were compressed together it would form a moon 25 km across.

So how much of this stuff – leftovers from the formation of the planets, debris from comets and asteroid collisions, etc. — encounters Earth? Satellite observations suggest that 100-300 metric tons of cosmic dust enter the atmosphere each day. This figure comes from the rate of accumulation in polar ice cores and deep-sea sediments of rare elements linked to cosmic dust, such as iridium and osmium.

But other measurements – which includes meteor radar observations, laser observations and measurements by high altitude aircraft — indicate that the input could be as low as 5 metric ton per day.

Knowing the difference could have a big influence on our understanding of things like climate change and, noctilucent clouds, as well as ozone and ocean chemistry.

“If the dust input is around 200 tons per day, then the particles are being transported down through the middle atmosphere considerably faster than generally believed,” said Plane. “If the 5-tonne figure is correct, we will need to revise substantially our understanding of how dust evolves in the Solar System and is transported from the middle atmosphere to the surface.”

When dust particles approach the Earth they enter the atmosphere at very high speeds, anything from 38,000 to 248,000 km/hour, depending on whether they are orbiting in the same direction or the opposite to the Earth’s motion around the Sun. The particles undergo very rapid heating through collisions with air molecules, reaching temperatures well in excess of 1,600 degrees Celsius. Particles with diameters greater than about 2 millimeters produce visible “shooting stars,” but most of the mass of dust particles entering the atmosphere is estimated to be much smaller than this, so can be detected only using specialized meteor radars.

The metals injected into the atmosphere from evaporating dust particles are involved in a diverse range of phenomena linked to climate change.

“Cosmic dust is associated with the formation of ‘noctilucent’ clouds – the highest clouds in the Earth’s atmosphere. The dust particles provide a surface for the cloud’s ice crystals to form. These clouds develop during summer in the polar regions and they appear to be an indicator of climate change,’ said Plane. “The metals from the dust also affect ozone chemistry in the stratosphere. The amount of dust present will be important for any geo-engineering initiatives to increase sulphate aerosol to offset global warming. Cosmic dust also fertilises the ocean with iron, which has potential climate feedbacks because marine phytoplankton emit climate-related gases.”

The CODITA team will also use laboratory facilities to tackle some of the least well-understood aspects of the problem

“In the lab, we’ll be looking at the nature of cosmic dust evaporation, as well as the formation of meteoric smoke particles, which play a role in ice nucleation and the freezing of polar stratospheric clouds,” said Plane. “The results will be incorporated into a chemistry-climate model of the whole atmosphere. This will make it possible, for the first time, to model the effects of cosmic dust consistently from the outer Solar System to the Earth’s surface.”

CODITA has received a EUR 2.5 million grant from the European Research Council to investigate the dust input over the next 5 years. The international team, led by Plane, is made up of over 20 scientists in the UK, the US and Germany. Plane presented information about the project at the National Astronomy meeting in the UK this week.

Source: Jodrell Bank Centre for Astrophysics

Posted on by Jason Major

So Long, SWAN…

Remember that newly-discovered comet we mentioned a couple of days ago?  Well, it’s gone. Poof. Into the Sun and never to return, it was a sungrazer’s final voyage.

The video above features images from the SOHO spacecraft and description from Bad Astronomer Phil Plait, with music by Kevin MacLeod.

Alas, poor SWAN… at least we knew him.

Read more about the history of Comet SWAN on the Sungrazing Comets site. Video credit: NASA/SOHO (and thanks to Phil Plait for the assembly.)

Posted on by Jason Major

A New Comet’s SWAN Dive Into the Sun

SOHO animation of the latest sun-diving comet (LASCO/NRL SOHO team)

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A new comet has been discovered by the SOHO team, and it — like Lovejoy before it, almost three months to the day — is headed directly toward the Sun. Discovered by SOHO’s SWAN instrument, the comet has been dubbed Comet SWAN… making this a real swan dive (or, perhaps more appropriately, its swan song.)

The animation above has a lot of random noise in it from recent solar outbursts… can you spot the comet? If not, read on…

Labeled frame of the LASCO image (courtesy of SpaceWeather.com)

There’s Comet SWAN, just above the darker silhouette of the bar that holds the shielding disk over the center of the imager (which blocks the glare from the Sun itself.)

The comet is likely another member of the Kreutz family of comets, an extended family of pieces that broke off a larger comet several hundred years ago (which itself may have been a survivor of a breakup in 371 B.C.!) Comet Lovejoy was also a Kretuz sungrazer but it was considerably larger and brighter, which may have helped it survive its Dec. 15 solar close encounter to re-emerge on the opposite side, surprising astronomers everywhere!

Read how some scientists think Comet Lovejoy held itself together.

SWAN may not be so lucky… but then again, we’ve been surprised before!

The comet will make perihelion — its closest approach to the Sun — on March 14. Stay tuned for more details!

Images via SpaceWeather.com.

Posted on by Jason Major

How Did Comet Lovejoy Survive Its Trip Around The Sun?

Comet Lovejoy re-emerging from behind the Sun on Dec. 15, 2011. (NASA/SDO)

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It was just about three months ago that the astronomy world watched in awe as the recently-discovered comet Lovejoy plummeted toward the Sun on what was expected to be its final voyage, only to reappear on the other side seemingly unscathed! Surviving its solar visit, Lovejoy headed back out into the solar system, displaying a brand-new tail for skywatchers in southern parts of the world (and for a few select viewers above the world as well.)

How did a loosely-packed ball of ice and rock manage to withstand such a close pass through the Sun’s blazing corona, when all expectations were that it would disintegrate and fizzle away? A few researchers from Germany have an idea.

Scientists from the Max Planck Institute for Extraterrestrial Physics and the Braunschweig University of Technology have hypothesized that Comet Lovejoy managed to hold itself together through the very process that, to most people, defines a comet: the outgassing of sublimated icy material.

As a comet near the Sun, the increased heating from solar radiation causes the frozen materials within the nucleus to sublimate — go directly and suddenly from solid to gas, skipping the liquid middle stage — and, in doing so, burst through the surface of the comet and create the long, hazy reflective tail that is so often associated with them.

Overview of the forces acting on sungrazing comets. (Illustration from paper.)

In the case of Lovejoy, which was on a direct path toward the Sun, the sublimation itself may have provided enough outward force across its surface to literally keep it together, according to the team’s research.

“The reaction force caused by the strong outgassing (sublimation) of the nucleus near the Sun acts to keep the nucleus together and to overcome the tidal disruption,” the paper claims.

In addition, the team states that the size of the comet’s nucleus can be derived using an equation that takes into consideration the combined forces of outgassing, the material composition of the comet’s nucleus, the comet’s own gravity and the tidal forces exerted by the comet’s close proximity to the Sun (i.e., the Roche limit).

Using that equation, the team concluded that the diameter of Comet Lovejoy’s nucleus is anywhere between 0.2 km and 11 km (.125 miles and 6.8 miles). Any smaller and it would have lost too much material during its pass (and had too little gravity); any larger and it would have been too thick for outgassing to provide enough counterbalancing force.

If this hypothesis is correct, taking a trip around the Sun may not mean the end for all comets… at least not those of a certain size!

Watch the video of Lovejoy’s Dec. 15 solar swing below:

The paper was submitted to the journal Icarus on March 8, 2012 by Bastian Gundlach. See the full text here.

Posted on by Jason Major

Mexican Lake Bears Witness To Ancient Impact

Lake Cuitzeo in central Mexico. (Via Julio Marquez, Wikipedia Commons)

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Exotic sediments found beneath the floor of Lake Cuitzeo in central Mexico support theories of a major cosmic impact event 12,900 years ago, report a 16-member international research team. The impact may have caused widespread environmental changes and contributed to the extinctions of many large animal species.

Images of single and twinned nanodiamonds show the atomic lattice framework of the nanodiamonds. Each dot represents a single atom. (Source: UCSB release.)

The team found a 13,000-year-old  layer of sediment that contains materials associated with impact events, such as soot, impact spherules and atomic-scale structures known as nanodiamonds. The nanodiamonds found at Lake Cuitzeo are of a variety known as lonsdaleite, even harder than “regular” diamond and only found naturally as the result of impact events.

The thin layer of sediment below Cuitzeo corresponds to layers of similar age found throughout North America, Greenland and Western Europe.

It’s thought that a large several-hundred-meter-wide asteroid or comet entered Earth’s atmosphere at a shallow angle 12,900 years ago, melting rocks, burning biomass and, in general, causing widespread chaos and destruction. This hypothesized event would have occurred just before a period of unusually cold climate known as the Younger Dryas.

The Younger Dryas has been associated with the extinction of large North American animals such as mammoths, saber-tooth cats and dire wolves.

“The timing of the impact event coincided with the most extraordinary biotic and environmental changes over Mexico and Central America during the last approximately 20,000 years, as recorded by others in several regional lake deposits,” said James Kennett, professor of earth science at UC Santa Barbara and member of the research team. “These changes were large, abrupt, and unprecedented, and had been recorded and identified by earlier investigators as a ‘time of crisis.’ ”

The exotic materials found in the sediment beneath Cuitzeo could not have been created by any volcanic, terrestrial or man-made process. “These materials form only through cosmic impact,” Kennett said.

The only other widespread sedimentary layer ever found to contain such an abundance of nanodiamonds and soot is found at the K-T boundary, 65 million years ago. This, of course, corresponds to the impact event that led to the extinction of the dinosaurs.

The researchers’ findings appeared March 5 in the Proceedings of the National Academy of Sciences. Read the news release from UC Santa Barbara here.