A team of astronomers from South Africa have noticed a series of supermassive black holes in distant galaxies that are all spinning in the same direction. Credit: NASA/JPL-Caltech
Gas around supermassive black holes tends to clump into immense clouds, periodically blocking the view of these huge X-ray sources from Earth, new research reveals.
Observations of 55 of these “galactic nuclei” revealed at least a dozen times when an X-ray source dimmed for a time as short as a few hours or as long as years, which likely happened when a gas cloud blotted out the signal seen from Earth. This is different than some previous models suggesting the gas was more uniform.
“Evidence for the clouds comes from records collected over 16 years by NASA’s Rossi X-ray Timing Explorer, a satellite in low-earth orbit equipped with instruments that measured variations in X-ray sources,” stated the Royal Astronomical Society.
“Those sources include active galactic nuclei, brilliantly luminous objects powered by supermassive black holes as they gather and condense huge quantities of dust and gas.”
The research was led by Alex Markowitz, an astrophysicist at the University of California, San Diego and the Karl Remeis Observatory in Bamberg, Germany.
Massive stars can devastate their surroundings, unleashing hot winds and blasting radiation. With a mass over 100 times heavier than the Sun and a luminosity a million times brighter than the Sun, Eta Carinae clocks in as one of the biggest and brightest stars in our galaxy.
The enigmatic object walks a thin line between stellar stability and tumultuous explosions. But now a team of international astronomers is growing concerned that it’s leaning toward instability and eruption.
In the 19th Century the star mysteriously threw off unusually bright light for two decades in an event that became known as the “Great Eruption,” the causes of which are still up for debate. John Herschel and others watched as Eta Carinae’s brightness oscillated around that of Vega — rivaling a supernova explosion.
We now know the star ejected material in the form of two big globes. “During the eruption the star threw off more than 10 solar masses, which can now be observed as the surrounding bipolar nebula,” said lead author Dr. Andrea Mehner from the European Southern Observatory. Miraculously the star survived, but the nebula has been expanding into space ever since.
Eta Carinae has been observed at the South African Astronomical Observatory — a 0.75m telescope outside of Cape Town — for more than 40 years, providing a wealth of data. From the start of observations in 1976 until 1998, astronomers saw an increase across the J, H, K and L bands — filters, which allow certain wavelength ranges of infrared light to pass through.
“This data set is unique for its consistency over a timespan of more than 40 years,” Mehner told Universe Today. “It provides us with the opportunity to analyze long-term changes in the system as Eta Carinae still recovers from its Great Eruption.”
In order to understand the longterm overall increase in light we have to look at a more recent discovery noted in 2005 when scientists discovered that Eta Carinae is actually two stars: a massive blue star and a smaller companion. The temperature increased for 15 years until the companion came very close to the massive star, reaching periastron.
This increase in brightness is likely due to an overall increase in temperature of some component of the Eta Carinae system (which includes the massive blue star, its smaller companion, and the shells of gas and dust that now enshroud the system).
After 1998, however, the linear trend changed significantly and the star’s brightness increased much more rapidly in the J and H bands. It’s getting bluer, which in astronomy, typically means it’s getting hotter.
However, it’s unlikely the star itself is getting hotter. Instead we are seeing the effect of dust around the star being destroyed rapidly. Dust absorbs blue light. So if the dust is getting destroyed, more blue light will be able to pass through the nebulous globes surrounding the system. If this is the case, then we’re really seeing the star as it truly is, without dust absorbing certain wavelengths of its light.
While the nebula is slowly expanding and the dust is therefore dissipating, the authors do not think it’s enough to account for the recent brightening. Instead Eta Carinae is likely rotating at a different speed or losing mass at a different rate. “The changes observed may imply that the star is becoming more unstable and may head towards another eruptive phase,” Mehner told Universe Today.
Perhaps Eta Carinae is heading toward another “Great Eruption.” Only time will tell. But in a field where most events occur on a timescale of millions of years, it’s a great opportunity to watch the system evolve on a human time scale. And when Eta Carinae reaches periastron in the middle of this year, tens of telescopes will be collecting its light, hoping to see a sudden turn of events that may help us explain this exotic system.
The paper has been accepted for publication in Astronomy & Astrophysics and is available for download here.
Wow. It’s always amazing to get new views of familiar sky targets. And you always know that a “feast for the eyes” is in store when astronomers turn a world-class instrument towards a familiar celestial object.
Such an image was released this morning from the European Southern Observatory (ESO). Astronomers turned ESO’s 2.2-metre telescope towards Messier 7 in the constellation Scorpius recently, and gave us the star-studded view above.
Also known as NGC 6475, Messier 7 (M7) is an open cluster comprised of over 100 stars located about 800 light years distant. Located in the curved “stinger” of the Scorpion, M7 is a fine binocular object shining at a combined magnitude of about +3.3. M7 is physically about 25 light years across and appears about 80 arc minutes – almost the span of three Full Moons – in diameter from our Earthly vantage point.
One of the most prominent open clusters in the sky, M7 lies roughly in the direction of the galactic center in the nearby astronomical constellation of Sagittarius. When you’re looking towards M7 and the tail of Scorpius you’re looking just south of the galactic plane in the direction of the dusty core of our galaxy. The ESO image reveals the shining jewels of the cluster embedded against the more distant starry background.
Messier 7 is middle-aged as open clusters go, at 200 million years old. Of course, that’s still young for the individual stars themselves, which are just venturing out into the galaxy. The cluster will lose about 10% of its stellar population early on, as more massive stars live their lives fast and die young as supernovae. Our own solar system may have been witness to such nearby cataclysms as it left its unknown “birth cluster” early in its life.
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Other stars in Messier 7 will eventually mature, “join the galactic car pool” in the main sequence as they disperse about the plane of the galaxy.
But beyond just providing a pretty picture, studying a cluster such as Messier 7 is crucial to our understanding stellar evolution. All of the stars in Messier 7 were “born” roughly around the same time, giving researchers a snapshot and a chance to contrast and compare how stars mature over there lives. Each open cluster also has a unique spectral “fingerprint,” a chemical marker that can even be used to identify the pedigree of a star.
For example, there’s controversy that the open cluster Messier 67 may actually be the birth place of our Sun. It is interesting to note that the spectra of stars in this cluster do bear a striking resemblance in terms of metallicity percentage to Sol. Remember, metals in astronomer-speak is any element beyond hydrogen and helium. A chief objection to the Messier 67 “birth-place hypothesis” is the high orbital inclination of the open cluster about the core of our galaxy: our Sun would have had to have undergone a series of improbable stellar encounters to have ended up its current sedate quarter of a billion year orbit about the Milky Way galaxy.
Still, this highlights the value of studying clusters such as Messier 6. It’s also interesting to note that there’s also data in what you can’t see in the above image – dark gaps are thought to be dust lanes and globules in the foreground. Though there is some thought that this dust is debris that may also be related to the cluster and may give us clues as to its overall rotation, its far more likely that these sorts of “dark spirals” related to the cluster have long since dispersed. M7 has completed about one full orbit about the Milky Way since its formation.
Another famous binocular object, the open cluster Messier 6 (M6) also known as the Butterfly Cluster lies nearby. Messier 7 also holds the distinction as being the southernmost object in Messier’s catalog. Compiled from Parisian latitudes, Charles Messier entirely missed southern wonders such as Omega Centauri in his collection of deep sky objects that were not to be mistaken for comets. We also always thought it curious that he included such obvious “non-comets” such as the Pleiades, but missed fine northern sky objects as the Double Cluster in the northern constellation Perseus.
Finding Messier 6: the view from latitude 30 degrees north before dawn in mid-February. Credit: Stellarium.
Messier 7 is also sometimes called Ptolemy’s Cluster after astronomer Claudius Ptolemy, who first described it in 130 A.D. as the “nebula following the sting of Scorpius.” The season for hunting all of Messier’s objects in an all night marathon is coming right up in March, and Messier 7 is one of the last targets on the list, hanging high due south in the early morning sky.
Interested in catching how Messier 7 will evolve, or might look like up close? Check out Messier 45 (the Pleiades) and the V-shaped Hyades high in the skies in the constellation Taurus at dusk to see what’s in store as Messier 7 disperses, as well as the Ursa Major Moving Group.
And be sure to enjoy the fine view today of Messier 7 from the ESO!
Got pics of Messier 7 or any other deep sky objects? Send ’em, in to Universe Today!
ESA's Gaia spacecraft as seen by the VLT (Credit: ESO)
Gaia, ESA’s long-anticipated mission to map the stars of our galaxy (as well as do a slew of other cool science things) is now tucked comfortably in its position in orbit around Earth-Moon L2, a gravitationally stable spot in space 1.5 million km (932,000 miles) away.
Once its mission begins in earnest, Gaia will watch about a billion stars an average of 70 times each over a five-year span… that’s 40 million observations every day. It will measure the position and key physical properties of each star, including its brightness, temperature and chemical composition, and help astronomers create the most detailed 3D map of the Milky Way ever.
But before Gaia can do this, its own position must be precisely determined. And so several of the world’s most high-powered telescopes are trained on Gaia, keeping track daily of exactly where it is up to an accuracy of 150 meters… which, with the ten-meter-wide spacecraft one and a half million kilometers away, isn’t too shabby.
Called GBOT, for Ground Based Orbit Tracking, the campaign to monitor Gaia’s position was first set up in 2008 — long before the mission launched. This allowed participating observatories to practice targeting on other existing spacecraft, like NASA’s WMAP and ESA’s Planck space telescopes.
The image above shows an image of Gaia (circled) as seen by the European Southern Observatory’s Very Large Telescope Survey Telescope (VST) atop Cerro Paranal in Chile, one of the supporting observatories in the GBOT campaign. The images were taken with the 2.6-meter Survey Telescope’s 268-megapixel OmegaCAM on Jan. 23, 6.5 minutes apart. With just the reflected sunlight off its circular sunshield, the distant spacecraft is about a million times fainter than what your eyes could see unaided.
Gaia mapping the stars of the Milky Way. (ESA/ATG medialab; background: ESO/S. Brunier)
It’s also one the closest objects ever imaged by the VST.
Currently Gaia is still undergoing calibration for its survey mission. Some problems have been encountered with stray sunlight reaching its detectors, and this may be due to the angle of the sunshield being a few degrees too high relative to the Sun. It could take a few weeks to implement an orientation correction; read more on the Gaia blog here.
Of the billion stars Gaia will observe, 99% have never had their distances accurately measured. Gaia will also observe 500,000 distant quasars, search for brown dwarfs and exoplanets, and will conduct experiments testing Einstein’s General Theory of Relativity. Find out more facts about the mission here.
Gaia launched on December 19, 2013, aboard a Soyuz VS06 from ESA’s spaceport in Kourou, French Guiana. Watch the launch here.
An extraordinary jet trailing behind a runaway pulsar is seen in this composite image. Credit: X-ray: NASA/CXC/ISDC/L.Pavan et al, Radio: CSIRO/ATNF/ATCA Optical: 2MASS/UMass/IPAC-Caltech/NASA/NSF
One of the fastest-moving pulsars ever observed is spewing out a record-breaking jet of high-energy particles that stretches 37 light years in length – the longest object in the Milky Way galaxy.
“We’ve never seen an object that moves this fast and also produces a jet,” said Lucia Pavan of the University of Geneva in Switzerland and lead author of a paper analyzing the object. “By comparison, this jet is almost 10 times longer than the distance between the sun and our nearest star.”
The pulsar, a type of neutron star, is has the official moniker of IGR J11014-6103, but is also known as the “Lighthouse nebula.” Astronomers say the pulsar’s corkscrew-like trajectory can likely be traced back to its birth in the collapse and subsequent explosion of a massive star. The curly-cue pattern in the trail suggests the pulsar is wobbling like a spinning top.
The team says that their findings suggest that “jets are common to rotation-powered pulsars, and demonstrate that supernovae can impart high kick velocities to misaligned spinning neutron stars, possibly through distinct, exotic, core-collapse mechanisms.”
The object was first seen by the European Space Agency satellite INTEGRAL. The pulsar is located about 60 light-years away from the center of the supernova remnant SNR MSH 11-61A in the constellation of Carina. Its implied speed is between 4 – 8 million km/hr (2.5 million and 5 million mph), making it one of the fastest pulsars ever observed.
IGR J11014-6103 also is producing a cocoon of high-energy particles that enshrouds and trails behind it in a comet-like tail. This structure, called a pulsar wind nebula, has been observed before, but the Chandra data show the long jet and the pulsar wind nebula are almost perpendicular to one another.
Usually, the spin axis and jets of a pulsar point in the same direction as they are moving.
“We can see this pulsar is moving directly away from the center of the supernova remnant based on the shape and direction of the pulsar wind nebula,” said co-author Pol Bordas, from the University of Tuebingen in Germany. “The question is, why is the jet pointing off in this other direction?”
One possibility requires an extremely fast rotation speed for the iron core of the star that exploded. A problem with this scenario is that such fast speeds are not commonly expected to be achievable.
“With the pulsar moving one way and the jet going another, this gives us clues that exotic physics can occur when some stars collapse,” said co-author Gerd Puehlhofer also of the University of Tuebingen.
Every Thanksgiving when I was home from college, at least one family member would turn to me and ask me how that astrology degree was going, or tell me about a new astrology article they read. It wasn’t that my family members really thought I was studying astrology or even believed astrology was scientific, it was just that they mixed up “astronomy” with “astrology.” In all fairness, for those who don’t follow either astrology or astronomy very closely, it might be considered an honest mistake.
So when a report from the National Science Foundation claimed a majority of young Americans believed astrology was scientific I had my doubts. But so did psychologist, Richard Landers from Old Dominion University who performed a small second study and found the report to be biased.
Since 1979, NSF surveys have asked Americans whether they view astrology — the study of how the movement of celestial bodies affects the here and now — as being scientific.
Their most recent survey showed that nearly half of all Americans (42 percent) believe astrology to be scientific. But what’s more alarming, according to the NSF, is that American understandings of science are moving in the wrong direction. It seems our golden year was in 2004, when 66 percent of Americans said astrology was not at all scientific. That number has been dropping ever since.
It should come as no surprise that those with a higher education are more willing to demote astrology entirely. In 2012, 72 percent of those with graduate degrees indicated that astrology is not scientific, compared with only 34 percent of those who didn’t graduate high school.
Shockingly, age was also related to perceptions of astrology. Younger respondents (ages 18-24) seemed to give astrology a high vote of confidence,with only 42 percent claiming that it isn’t scientific. So roughly six in every 10 young adults believe astrology is absolutely scientific.
But such dramatic conclusions are being drawn from a single question: “Is astrology scientific?” It’s based on the crucial assumption that people are correctly interpreting the word “astrology.”
Landers guessed that the survey respondents might be mixing up the term “astrology” with “astronomy.” So he performed a quick survey himself, using Amazon Mechanical Turk (MTurk) — a crowdsourcing internet marketplace. He collected 100 responses to a survey that asked three questions:
— Please define astrology in 25 words or less.
— Do you believe astrology to be scientific?
— What is your highest level of education completed?
His initial assessment — without taking into account how the respondent defined astrology — showed results very similar to the original survey provided by the NSF — approximately 30 percent found astrology to be scientific. While this percentage is less than what the NSF report found, Landers believes this is due to a user bias (MTurk users tend to be more educated and older than the average American).
But once Landers included the answer to the first question into his results, he saw a very clear trend: those who defined astrology correctly did not believe it to be scientific, while those who confused astrology with astronomy did believe it to be scientific.
Data collected from 100 participants using MTurk. Image Credit: R. Landers
Among those that correctly identified astrology, only 13.5 percent found it to be “pretty scientific.” And only one person found it to be “very scientific.” Among those that confused astrology with astronomy, the discipline was overwhelmingly seen as scientific.
“My little quick study doesn’t ‘overturn’ the NSF results” Landers told Universe Today. “It only suggests that the NSF results are probably biased to some degree.”
With such small number statistics Landers certainly didn’t prove the NSF results wrong, but he does call the study into question. Landers also noted an additional study from the European Commission which corroborated his findings.
I for one would love to see the NSF conduct a more detailed study. Including a definition of astrology in the next round of surveys would certainly bring clarification and shed light on the root of the problem.
—
Update: After posting this article, a reader informed me of a critique of Richard landers’ assessment, posted by The Washington Post’s Jim Lindgren. He conducted another follow-up study to explore the issue. In his own sample, Lindgren found that probably only one respondent out of 108 confused “astrology” with “astronomy.” He claims it’s unlikely the NSF report was biased at all.
However, the back and forth banter between experts suggests these words and their corresponding definitions do need to be clarified. Science journalists have their work cut out for them.
Looking for something off of the beaten celestial path to observe? The coming weeks will offer telescope users a rare chance to catch a well known asteroid, as it puts on its best show for over two decades.
Over the coming weeks, 2 Pallas, one of the “big four” asteroids – or do you say minor/dwarf planet/planetoid? – reaches a favorable observing point known as opposition. Gliding northward through the constellations of Hydra and Sextans through February and March 2014, 2 Pallas presents a favorable binocular challenge for both northern and southern hemisphere observers as it rises to the east opposite to the setting Sun and transits the local meridian around midnight.
And although 2 Pallas reaches opposition roughly every 16 months as seen from our Earthly vantage point, 2014 provides a chance to catch it under exceptional circumstances. And to top it off, the other “Big 4” asteroids – 1 Ceres, 3 Juno and 4 Vesta – are all currently visible as well and reach opposition in the January through April time frame.
2 Pallas as imaged by the Hubble Space Telescope. Credit: NASA
Pallas and its brethren also have a checkered history though the course of 19th century astronomy. The second minor planet to be discovered, Heinrich Wilhelm Olbers spied 2 Pallas near opposition on the night of March 28th, 1802. Olbers made this discovery observing from his home rooftop observatory in Bremen, Germany using a five foot – telescopes were often measured in focal length rather than aperture in those days – Dollond refractor.
Olbers discovered 2 Pallas on the border of the astronomical constellations of Virgo and Coma Berenices shining at magnitude +7.5.
A simulation of the orbit of 2 Pallas near opposition this month. Credit: NASA/JPL Horizons.
If the name Olbers sounds familiar, it’s because he also lent it to the paradox that now bears his name. Obler’s paradox was one of the first true questions in cosmology posed in a scientific framework that asked: if the universe is actually infinite in time and space, then why isn’t the sky infinitely bright? And, on a curious side note, it was American horror author Edgar Allan Poe that delivered the answer.
But now back to our solar system. Olbers also discovered 4 Vesta just five years after Pallas.
He was definitely on a roll. The discoveries of these space rocks also grabbed the attention of Olbers contemporary, Johann Bode. Bode had formulated a law now known as the Titus-Bode Law that seemed to put the spacing of then known bodies of the solar system in tidy order. In fact, the Titus-Bode law seemed to predict that a body should lie between Mars and Jupiter, and for a brief time in the 18th century — and again in 2006 when the International Astronomical Union let Eris and Pluto in the door before kicking them back out — Ceres, Pallas, Juno and Vesta were all considered planets.
A size comparison of the first ten asteroids discovered compared to Earth’s moon. Wikimedia Commons graphic in the Public Domain.
Today, we now know that 2 Pallas is a tiny world about 575 kilometres in diameter. 2 Pallas orbits the Sun once every 4.62 years and has a relatively high inclination of 34.8 degrees relative to the ecliptic. Pallas has no confirmed satellites, though one was once hinted at during a May 29th, 1979 stellar occultation. And though we’ve yet to send a mission to examine Pallas up close, there were early planning considerations to send NASA’s Dawn spacecraft there after its visit to 1 Ceres.
The path of 2 Pallas from February 16th though March 21st. Created by the author using Stellarium.
This month, look for 2 Pallas as a +7th magnitude wandering star at dusk. Mid-February finds 2 Pallas in the constellation Hydra, and it crosses briefly into Sextans starting on March 22nd until it passes just three degrees east of the 2nd magnitude Alphard (Alpha Hydrae) on March 1st, making a good guidepost to find it at its brightest.
2 Pallas last broke +7th magnitude visibility as seen from Earth in 1991 and won’t do so again til 2028. This is because 18.5 Earth years very nearly equals four orbits of Pallas around the Sun, bringing the two worlds back “into sync.” According to calculations by Belgian astronomer Jean Meeus, the 2014 opposition season offers the closest passage to Earth for Pallas from 1980-2060. Pallas can appear at a maximum brightness of magnitude +6.5 — just on the threshold of naked eye visibility — as seen from Earth.
A narrow field finder chart for 2 Pallas with sample comparison magnitudes, decimal points omitted. Created by the author using Stellarium.
Opposition for Pallas occurs on February 22nd, 2014, when the asteroid is 1.23 AUs distant from our fair planet. Watch for 2 Pallas near opposition this year moving at just under half a degree a day — about the diameter of the Full Moon — headed northward at closest approach.
Hunting asteroids at the eyepiece can be a challenge, as they visually resemble pinpoint stars and show no apparent disks even at high magnification. Sketching or photographing the field of view on successive nights is a fun and easy way to cross this object off of your life list. For those who own scopes with digital setting circles, Heavens-Above is a great quick look source for current coordinates.
2 Pallas just passed perihelion at 2.13 Astronomical Units from the Sun on December 6th, 2013, and passes closest to Earth on February 24th at 1.2 A.U.s distant.
Don’t miss the chance to spy this fascinating an enigmatic worldlet coming to a sky near you this season!
-Got pics of 2 Pallas and friends? Be sure to send ‘em in to Universe Today!
A global map showing where all the volunteers are based. Image Credit: Zooniverse
Zooniverse — the renowned home of citizen science projects — is now one million strong. That’s one million registered volunteers since the project began less than seven years ago.
It all began when Galaxy Zoo launched in July 2007. The initial response to this project was overwhelming. Since then the Zooniverse team has created almost 30 citizen science projects ranging from astronomy to zoology.
“We are constantly amazed by the effort that the community puts into our projects,” said the Zooniverse team in an email regarding the news late last week.
Many projects have produced unique scientific results, ranging from individual discoveries to classifications that rely on input from thousands of volunteers. As of today there are 60+ papers listed on the websites publications page, many of which have made the news.
In the first two weeks after Galaxy Zoo’s launch, registered citizen scientists classified more than a million galaxies. Each volunteer was presented with an image from the Sloan Digital Sky Survey and asked to classifiy the galaxy as belonging to one of six categories: elliptical, clockwise spiral, anticlockwise spiral, edge-on, merger, or unsure.
An example of an unknown galaxy needing classification. Image credit: Galaxy Zoo
But citizen scientists weren’t simply labeling galaxies, they were helping astronomers to answer crucial questions and raise new ones about our current understandings of galaxy evolution. One significant finding showed that bar-shaped features in spiral galaxies has doubled over the latter half of the history of the Universe. This confirms that bars signify maturity in spiral galaxies and play an important role in shutting down star formation.
Another finding downplayed the importance of collisions in forming supermassive black holes. Citizen scientists found 13 bulgeless galaxies — suggesting they had never experienced a major collision — with supermassive black holes, nonetheless. All healthy black holes, with masses at least millions of times that of the Sun, must have grown through less dramatic processes.
Planet Hunters — a citizen science project developed in 2010 — has also seen wide success. Ordinary citizens examine the Kepler Space Telescope’s light curves of stars and flag any slight dips in brightness that might indicate a planet crossing in front of the star. Many eyes examine each light curve, allowing some to cross check others.
An example light curve asking for any obvious dips. Image Credit: Planet Hunters
In roughly three years, citizen scientists examined more than 19 million Kepler light curves. Contrary to what many astronomers expected, ordinary citizens were able to spot transiting objects that many computer algorithms missed.
In 2012, Planet Hunter volunteers, Kian Jek and Robert Gagliano discovered an exoplanet in a four-star system. The Neptune-size planet, labeled “Planet Hunters 1” (PH1), orbits its two parent stars every 138 days. A second pair of stars, approximately 90 billion miles away, are also gravitationally bound to the system. This wacky system was later confirmed by professional astronomers.
In 2013, Planet Hunter volunteers discovered yet another planet candidate, which, if confirmed, would make a known six-planet system really the first seven-planet system. The five innermost planets are smaller than Neptune, while the two outer planets are gas giants. All orbit within Earth’s orbit around the Sun.
These are only a few of Zooniverse’s citizen science projects. Others allow ordinary citizens to help analyze how whales communicate with one another, study the lives of the ancient Greeks, and even look at real life cancer data. So join today and become number one million and one.
Zooniverse is produced by the Citizen Science Alliance, which works with many academic and other partners worldwide.
Chelyabinsk fireball recorded by a dashcam from Kamensk-Uralsky north of Chelyabinsk where it was still dawn. A study of the area near this meteor air burst revealed similar signatures to the Tall el_Hammam site.
Wonder and terror. Every time I watch the dashcam videos of the Chelyabinsk fireball it sends chills down my spine. One year ago today, February 15, 2013, the good citizens of Chelyabinsk, Russia and surrounding towns collectively experienced these two powerful emotions as they witnessed the largest meteorite fall in over 100 years.
Incredible compilation of dashcam and security camera videos of the fireball
The Chelyabinsk fall, the largest witnessed meteorite fall since the Tunguska event in 1908, exploded with 20-30 times the force of the atomic bomb over Hiroshima at an altitude of just 14.5 miles (23 km). Before it detonated into thousands of mostly gravel-sized meteorites and dust, it’s estimate the incoming meteoroid was some 66 feet (20-meters) end to end, as tall as a five-story building. The shock wave from the explosion shattered windows up and down the city, injuring nearly 1,500 people.
Atmospheric friction pressure on the Chelyabinsk meteoroid caused it to explode to pieces and send a shock wave across the land below. Pictured is a selection of typical small, fusion-crust covered Chelyabinsk meteorites recovered shortly after the fall. The U.S. penny is 9mm in diameter. Credit: Bob King
For nearby observers it briefly appeared brighter than the sun. NASA Meteorite researcher Peter Jenniskens conducted an Internet survey of eyewitnesses and found that eye pain and temporary blindness were the most common complaints from those who looked directly at the fireball. 20 people also reported sunburns including one person burned so badly that his skin peeled:
Map showing the trajectory of the main fireball in yellow (and two additional explosions at top left). The pink oval, called the strewnfield, is where the densest concentration of meteorites were found. Click to see additional maps. Credit: Svend Buhl and K. Wimmer
“We calculated how much UV light came down and we think it’s possible,” Jenniskens said. Perhaps surprisingly, most of the meteoroid’s mass – an estimated 76% – burned up and was converted to dust during atmospheric entry. It’s estimated that only 0.05% of the original meteoroid or 9,000 to 13,000 pounds of meteorites fell to the ground.
No video I’ve seen better captures the both the explosion of the fireball and ensuring confusion and chaos better than this one.
The largest fragment, weighing 1,442 lbs. (654 kg), punched a hole in the ice of Lake Chebarkul. Divers raised it from the bottom muck on Oct. 16 last year and rafted it ashore, where scientists and excited onlookers watched as the massive space rock was hoisted onto a scale and promptly broke into three pieces. Moments later the scale itself broke from the weight.
The 26-foot-wide (8-meter) hole punched in the ice of Chebarkul Lake by the largest fragment of the Chelyabinsk meteorite. Credit: Eduard Kalinin
There were plenty of meteorite to go around as local residents tracked down thousands of fragments by looking for holes pierced in the snow cover by the hail of space rocks. Working with hands and trowels, they dug out mostly small, rounded rocks covered in fresh black fusion crust, a 1-2 mm thick layer of rock blackened and melted rock from frictional heating by the atmosphere. According to the Meteoritical Bulletin Database entry, the total mass of the recovered meteorites to date comes to 1,000 kg (2,204 lbs.) with locals finding up to more than half of that total.
Animation of the orbit Chelyabinsk meteoroid via Ferrin and Zuluaga. Meteoroid is the name given a meteor while still orbiting the sun before it enters Earth’s atmosphere.
Thanks to the unprecedented number of observations of the fireball recorded by dashcams, security cameras and eyewitness accounts, astronomers were able to determine an orbit for Although some uncertainties remain, the object is (was) a member of the Apollo family of asteroids, named for 1862 Apollo, discovered in 1932. Apollos cross Earth’s orbit on a routine basis when they’re nearest the sun. Chelyabink’s most recent crossing was of course its last.
Chelyabinsk meteorites tell the tale of an earlier impact with another asteroid 4.452 billion years ago. Many specimens are pale white with small chondrules typical of LL5 chondrites. A closer look shows fine, dark shock veins of melted glass. Other fragments are made of pure impact melt, rock shocked-heated, melted and blackened by impact. Credit: Bob King
Chelyabinsk belongs to a class of meteorites called ordinary chondrites, a broad category that includes most stony meteorite types. The chondrites formed from dust and metals whirling about the newborn sun some 4.5 billion years ago; they later served as the building blocks for the planets, asteroids and comets that populate our solar system. Chondrites are further subdivided into many categories. Chelyabinsk belongs to the scarce LL5 class — a low iron, low metal stony meteorite composed of silicate materials like olivine and plagioclase along with small amounts of iron-nickel metal.
Most of the Chelyabinsk meteorites were shattered and broken during the explosion / shock blast, revealing brecciation, metal and shock veins in their interiors. Credit: Bob KingA thin slice of Chelyabinsk impact melt breccia. Flows of once-molten rock (paler gray) surround islands of less altered material. A small iron nickel nodule is seen at lower left. Credit: Bob King
A closer look at Chelyabinsk meteorites reveals a fascinating story of ancient impact. Remarkably, the seeds of the meteoroid’s atmospheric destruction were sown 115 million years after the solar system’s formation when ur-Chelyabinsk was struck by another asteroid, suffering a powerful shock event that heated, fragmented and partially melted its interior. Look inside a specimen and the signs are everywhere – flows of melted rock, spider webby shock veins of melted silicates and peculiar, shiny cleavages called “slickensides” where meteorites broke along pre-existing fracture planes.
Slickensides on a Chelyabinsk meteorite fragment where the fragment broke along a pre-existing fracture plane. Credit: Bob King
Jenniskens calculated that the object may have come from the Flora family of S-type or stony asteroids in the belt between Mars and Jupiter. Somehow Chelyabinsk held together after the impact until nearly the time it met its fate with Earth’s atmosphere. Researchers at University of Tokyo and Waseda University in Japan discovered that the meteorite had only been exposed to cosmic rays for an unusually brief time for a Flora member – just 1.2 million years. Typical exposures are much longer and indicate that the Chelyabinsk parent asteroid only recently broke apart. Jenniskens speculates it was likely part of a loosely-bound, rubble pile asteroid that may have broken apart during a previous close encounter with Earth in the last 1.2 million years. The rest of the rubble pile might still be orbiting relatively nearby as part of the larger population of near-Earth asteroids.
Rivulets of melted rock line the fusion crust of melted rock on this small Chelyabinsk meteorite. Credit: Bob King
Good thing Chelyabinsk arrived pre-fractured. Had it been solid through and through, more of the original asteroid might have survived its fiery descent and wreaked even more havoc in in its wake.
We’re fortunate that Chelyabinsk contains a fantastic diversity of features and that we have so many pieces for study. Surveys have found some 500 near-Earth asteroids. No doubt some are part of the parent body of Chelyabinsk and may grace our skies on some future date. Whatever happens, Feb. 15, 2013 will go down as a very loud “wake-up call” for our species to implement more asteroid-hunting programs both in space and on the ground. Enjoy a few more photos of this incredible gift from space:
This Chelyabinsk “nosecone” or “bullet” weighs just 0.35g. It displays a beautiful streamlined form from its flight through the atmosphere. Credit: Bob KingCheck out the bubble texture on this one. Heated by friction with the air, this fragment shows bubbly crust from escaping gases. Credit: Bob KingSlice of Chelyabinsk showing mildy shocked areas (light brown) cut by thick dark veins of shock-darkened material. Credit: Bob KingSome Chelyabinsk individuals show interesting variations in color that have nothing to do with rusting. It’s believed that varying amounts of oxygen available to the speeding rocks during the meteorite break up created the brownish-red coloration on some fusion crusts. Credit: Bob KingI saved the weirdest for last – a smaller Chelyabinsk meteorite appears to have followed closely enough behind the larger for their still-molten fusion crusts to have welded them together. Just my speculation. Credit: Bob King
A view of the Cat's Eye Nebula during the calibration phase of Gaia, a Milky Way-mapping telescope. Credit: ESA/DPAC/Airbus DS
Here’s a glimpse of how a telescope gets ready for its main mission. The European Space Agency’s Gaia telescope is in the middle of a commissioning phase before mapping out the locations of stars and other objects in the Milky Way. While the nominal mission is not to take pictures, it is through these images that controllers can verify that the telescope is tuned properly to do its work.
What you’re seeing is data from the Gaia camera’s “sky-mapper strips” that are actually intensity maps rendered in black and white, ESA explained. You can see in the picture above that the shot on the left is a bit blurry, while the one on the right looks a bit sharper. That’s because controllers better calibrated the charged coupled devices to the spacecraft’s spin rate, ESA said.
A calibration image of M94 taken by Gaia, a Milky Way-mapping telescope, in early 2014. The gap is due to the image appearing on two separate CCDs. Credit: ESA/DPAC/Airbus DSWrites the European Space Agency in February 2014: “This is a rotated Gaia image section (left; extracted from the cluster image of NGC 2516 above), compared to a Digital Sky Survey image taken from the ground (right).” Credit: ESA/DPAC/Airbus DS/DSS
