APOD: Chelyabinsk Meteor Flash (2013 Feb 23)

[APOD Robot]

Chelyabinsk Meteor Flash

Explanation: A meteoroid fell to Earth on February 15, streaking some 20 to 30 kilometers above the city of Chelyabinsk, Russia at 9:20am local time. Initially traveling at about 20 kilometers per second, its explosive deceleration after impact with the lower atmosphere created a flash brighter than the Sun. This picture of the brilliant bolide (and others of its persistent trail) was captured by photographer Marat Ametvaleev, surprised during his morning sunrise session creating panoramic images of the nearby frosty landscape. An estimated 500 kilotons of energy was released by the explosion of the 17 meter wide space rock with a mass of 7,000 to 10,000 tons. Actually expected to occur on average once every 100 years, the magnitude of the Chelyabinsk event is the largest known since the Tunguska impact in 1908.

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[Case]

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On the APOD page, the links for previous, discuss and next point to the wrong date.

[bystander]

< | Archive | Index | Search | Calendar | RSS | Education | About APOD | Discuss | >

On the APOD page, the links for previous, discuss and next point to the wrong date.

Thanks, the PTBs have been notified.

[Boomer12k]

Discuss link really needs to be fixed...hope it is done soon.

:---[===] *

[flamencoprof]

May I suggest that "500 kilotons of energy " should read "energy equivalent to 500 kilotons of TNT"?

[henrystar]

Someone pointed out to me why there were so many injuries due to glass cuts: people saw the light flash, and like fools ... went to look out the window, just as the slower-moving sound wave arrived and smashed the window. During a war, NO one would ever look out a window after a bright flash.

[Ann]

It sure looks as if Chelyabinsk had a second Sun that day! But it burnt out fast.

Reminds me of the old debates about what makes the Sun shine. Is it made of coal, for example? But how long would a solar mass of coal last before it burnt out? (Answer: A few thousand years at most. Sorry.)

Lord Kelvin, the man behind the temperature scale, suggested that the Sun shone by being hit by meteoroids!

http://www.nobelprize.org/nobel_prizes/ ... es/fusion/ wrote:

Kelvin, like Helmholtz, was convinced that the sun's luminosity was produced by the conversion of gravitational energy into heat. In an early (1854) version of this idea, Kelvin suggested that the sun's heat might be produced continually by the impact of meteors falling onto its surface. Kelvin was forced by astronomical evidence to modify his hypothesis and he then argued that the primary source of the energy available to the sun was the gravitational energy of the primordial meteors from which it was formed.

Thus, with great authority and eloquence Lord Kelvin declared in 1862:

That some form of the meteoric theory is certainly the true and complete explanation of solar heat can scarcely be doubted, when the following reasons are considered: (1) No other natural explanation, except by chemical action, can be conceived. (2) The chemical theory is quite insufficient, because the most energetic chemical action we know, taking place between substances amounting to the whole sun's mass, would only generate about 3,000 years' heat. (3) There is no difficulty in accounting for 20,000,000 years' heat by the meteoric theory.

So the reasoning about the Chelyabinsk meteor and the Sun somehow comes full circle. Not that the Sun doesn't shine by hydrogen fusion, and not that the Sun isn't a more mature piece of cosmic Cheddar than a twenty million year old one, of course, but that's another matter...

Ann

[neufer]

Actually expected to occur on average once every 100 years, the magnitude of the Chelyabinsk event is the largest known since the Tunguska impact in 1908.

The last known comparable event apparently took place in Brazil 83 years ago:

1930 Curuçá River event.

<<Curuçá River is a river of Amazonas state in north-western Brazil. On August 13, 1930 the area near latitude 5° S and longitude 71.5° W experienced a meteorite air burst, also known as the Brazilian Tunguska. The mass of the meteorite was estimated at between 1000 and 25000 tons, with an energy release estimated between 0.1 and 5 Megatons.>>

Assuming that there were probably, at least, 6 UNknown such events in between (e.g., ocean, Sahara, Antarctica, during a thunderstorm, etc.) that would give an expected occurrence of once every dozen years.

Tunguska was 25 times more powerful and, at least, 25 times rarer (i.e., once every 300 years):

http://en.wikipedia.org/wiki/List_of_meteor_air_bursts

[zbvhs]

People say that these large meteors "explode". What exactly is the mechanism of that explosion? Smaller meteorites that have been found soon after impact are hot to the touch but that heat apparently doesn't reach the interior of the rock. So, what causes large ones to break up? Are they simply not strong enough to withstand the forces imposed by atmospheric entry?

[neufer]

People say that these large meteors "explode". What exactly is the mechanism of that explosion? Smaller meteorites that have been found soon after impact are hot to the touch but that heat apparently doesn't reach the interior of the rock. So, what causes large ones to break up?

Are they simply not strong enough to withstand the forces imposed by atmospheric entry?

• Yes.

[Byork]

A 17 meter asteroid weighing 7000 to 10000 tons_? The Earth definitely needs more of these. And, what could be said of asteroid mining, other than: if you can't go to the mountain, then the mountain should come to you.
As a matter of interest, a similar asteroid or bolide fell near the Black Sea a few weeks earlier. Townsfolk in Fatsa Turkey reported seeing a bright flash of light in the evening hours followed by minor land tremor. The object was never investigated but it is obvious that it was either a very large space junk object falling from the sky or a small asteroid composed of metal and rock.

[Redbone]

Best picture that I've seen, thanks.

I agree with neufer, an event of this magnitude is probaly more common than every 100 years. In my youth, when I sometimes stayed up all night and stayed outdoors, I saw two large meteorites. One split in half as it steaked across the sky and one I could hear.

[Chris Peterson]

A 17 meter asteroid weighing 7000 to 10000 tons_? The Earth definitely needs more of these. And, what could be said of asteroid mining, other than: if you can't go to the mountain, then the mountain should come to you.

Not very efficient. Seems like we might have a few hundred pounds of surviving material. If that. Of which less than 10% is iron, and any genuinely valuable elements are in trace amounts only.

[Chris Peterson]

People say that these large meteors "explode". What exactly is the mechanism of that explosion? Smaller meteorites that have been found soon after impact are hot to the touch but that heat apparently doesn't reach the interior of the rock. So, what causes large ones to break up? Are they simply not strong enough to withstand the forces imposed by atmospheric entry?

Discussed in some detail here.

Most meteorites recovered immediately after falling are not warm, but cool or cold to the touch. When the meteor stops burning, the meteorite is at about whatever temperature it was in space, which is typically somewhere between a little less than freezing to uncomfortably warm. On average, it is reasonable to imagine it around room temperature, as you'd expect for a rock sitting in the Sun (which is what the parent body was doing before it encountered the atmosphere). A few seconds of rapid burning, with the heat carried away by ablation, doesn't have much effect on the interior temperature. However, at this point, the meteorite is some tens of kilometers high, and spends several minutes falling at ~ 100 m/s through air that averages -40°C, so smaller stones will get very cold. Larger ones will retain more of their original heat inside. So usually, at the time they hit the ground, the outer surface is near ambient, and the interior is very cold. There are several reports of meteorites breaking open on impact and immediately frosting on the exposed interior surface.

[woodman]

Have the scientists estimated the angle of incidence of the meteor? Would a more perpendicular entry increase the meteor's explosive energy, or is that solely a factor of its mass?

[neufer]

A 17 meter asteroid weighing 7000 to 10000 tons_? The Earth definitely needs more of these. And, what could be said of asteroid mining, other than: if you can't go to the mountain, then the mountain should come to you.

Not very efficient. Seems like we might have a few hundred pounds of surviving material. If that. Of which less than 10% is iron, and any genuinely valuable elements are in trace amounts only.

Fragments of Meteorite Worth Their Weight in Gold
by Jason Major on May 1, 2012

Actually it’s more like 3.5 times their weight in gold, according to today’s market value… and meteorite experts from SETI and NASA’s Marshall Space Flight Center.

During the daylight hours of April 22, 2012, reports came in from all over the north central California area of an extremely bright fireball — described as a “glittering sparkler” — and accompanying loud explosion. It was soon determined that this was the result of a meteoroid about the size of a minivan entering the atmosphere and disintegrating. It was later estimated that the object weighed about 70 metric tons and detonated with a 5-kiloton force [i.e., ~1% of Chelyabinsk Meteor mass/energy].

Over a thousand meteorite hunters scrambled to the area, searching for any traces of the cosmic visitor’s remains. After a few days, several pieces of the meteorite were found and reported by five individuals, adding up to 46 grams in total. Those pieces could be worth over $9,000 USD, according to Bill Cooke of NASA’s Meteoroid Environment Office at Marshall Space Flight Center. Based on today’s market, that’s about 3.6 times the value of gold (about $1,660 per troy ounce — 31.1 grams).

The high value is due to the extreme rarity of the meteorite fragments. The California fireball is now known to have been created by a CM chondrite, a type of carbonaceous meteorite with material characteristics similar to comets.

According to Franck Marchis, Planetary Astronomer at the Carl Sagan Center of the SETI Institute and one of the coordinators of the meteorite reporting teams, CM chondrites appear to have been altered by water, and have deuterium-to-hydrogen ratios in line with what’s been measured in the tails of comets Halley and Hyakutake. They also have been found to contain organic compounds and amino acids, lending to the hypothesis that such meteorites may have helped supply early Earth with the building blocks for life. But due to their fragile composition, they are also incredibly rare. Only 1% of known meteorites are CM chondrites, making even the small handful of fragments found in California very valuable. “This will be only the third observed CM fall in the US, after Crescent, OK, in 1936, (78 g) and Murray, KY, in 1950 (13 kg),” Marchis told Universe Today.

As far as what the finders will do with the fragments, that’s entirely up to them. “They can sell them on eBay or they can lend them to the scientists… or make a donation.” Marchis said. Just goes to show that all that glitters really isn’t gold — it could be even better.

[perdostos]

Have the scientists estimated the angle of incidence of the meteor? Would a more perpendicular entry increase the meteor's explosive energy, or is that solely a factor of its mass?

Hi everybody!

As I read spaceflightnow.com the meteor has entered atmosphere at angle of 20 degrees.

[Chris Peterson]

Have the scientists estimated the angle of incidence of the meteor? Would a more perpendicular entry increase the meteor's explosive energy, or is that solely a factor of its mass?

The entry angle was approximately 20° from horizontal. Had it arrived at a steeper angle, it probably would have exploded higher, resulting in lower energy densities at the ground and therefore less damage. The total thermal and acoustic energy could have been higher or lower, depending on the dynamics of the breakup.

[aildoux]

I've seen many videos of this meteor but this is the first actual still picture taken of it that I've seen. Could it be the only one yet?

[woodman]

Have the scientists estimated the angle of incidence of the meteor? Would a more perpendicular entry increase the meteor's explosive energy, or is that solely a factor of its mass?

The entry angle was approximately 20° from horizontal. Had it arrived at a steeper angle, it probably would have exploded higher, resulting in lower energy densities at the ground and therefore less damage. The total thermal and acoustic energy could have been higher or lower, depending on the dynamics of the breakup.

so...a higher point of explosion would mean occurring in a less dense part of the atmosphere. I assumed it was all about atmospheric pressure. If it is also heat buildup, why wouldn't it still happen at the same point? A flatter trajectory is longer, but through thinner air, on average, so heat would build more slowly than on a steep descent - still confused! thanks.

[neufer]

I've seen many videos of this meteor but this is the first actual still picture taken of it that I've seen. Could it be the only one yet?

• No... but it is definitely the best

Google Translation of Marat Ametvaleev ("marateaman") :

[list]The explosion of a meteorite in the sky over the Chelyabinsk.
Full photo report with comments.[/list]----------------------------------------------------------------

• Morning. Beginning.

The morning was frosty (About -17 C), windless and cloudless. And because the day before was a very warm day (the temperature was near zero) - the trees were covered with frost. I decided to go to the scene to photograph their favorite point close to home. Around 9:00 am, I was at the scene and began to make the first shots. Unusual and remarkable in the sky before the object was not. After making a few shots from different angles, I moved to a different camera angle. The camera is pointed in the direction of the rising sun (the sun appears to have remained a matter of minutes.)
----------------------------------------------------------------

• Flash.

Yes! The appearance of the object was a surprise! The camera was on a tripod and aimed almost at the side (pictured above), which appeared object. I leaned over to the camera to change the camera angle and make another shot the scene. At this point, peripheral vision, I saw a bright flash. At first it was small. Immediately turned the camera to the object, and at this time of the outbreak has reached its peak, and everything was bathed in bright light.
----------------------------------------------------------------

• Awareness.

The first thing I thought was not a meteorite, a nuclear bomb. Then he remembered about the media reports about a possible asteroid and its approach to the Earth. Then there was the idea of an airplane that crashed.
----------------------------------------------------------------

• Feelings.

In the first seconds quickened heartbeat and breathing, as well as shaking hands, which is likely to be the consequences of the shock of what he saw. When the flash was as bright as possible, I felt strong enough heat in the face (it lasted just a split second.)

At the time of bright light, I also felt a strong pain in the eyes of intolerable glare. No more physical sensations were not. Then, 2 minutes after the flash, there was a series of explosions - the sound was neraskatisty and clear and very powerful. The first explosion was very strong, but I felt only the cotton. No physical sensations and vibrations I felt as was far from concrete structures and roads. Immediately after a series of bombings over the pine forest, near a large number of birds rose up and flew in all directions. Heartbeat, breathing, and hand tremors only strengthened. Shock was even greater.
----------------------------------------------------------------

• Shooting.

As mentioned earlier, immediately after seeing the first outbreak, I turned the camera towards the subject and take a single picture. He was heavily overexposed, I frantically started trying to fix the exposure to capture neperesvechenny object. I do not remember exactly how I made ​​the frame with hot particles inside track. Everything was a blur, and occurred in a matter of seconds. Next, the actions I remember vaguely. I did everything "on automatic." Shock did not allow to concentrate to put the correct values ​​and choose a great camera angles. I remember that I dropped in the snow control from the camera to change the filter on the lens. Only after a series of blasts I came a little to himself, was able to set the correct exposure, choose camera angles and shoot a few panoramas with residual cloud of meteorite.

A few words about how to change the nature around. Feels like the sky was bluer and transparent. The sun had already risen, but its brightness was like no more morning sun, and the sun is at its zenith.
----------------------------------------------------------------

• P. S.

Already after I shot footage, and cloud almost dissipated, I collected all the techniques and some time just standing. Observe nature around them, and considered their experiences. First thoughts were of loved ones, it was very difficult to get through, because network was overloaded. These thoughts haunted, were not allowed to recognize the scale of the incident and its consequences. On the way home I thought about the ownership of something global and very important. Only when I got in touch with his family, was able to concentrate on what they saw. First news on the Internet is not given any clarity. I immediately set about processing the footage and prepare it for publication. During the day, began to receive various news and various assumptions. Depressive mood is injected into society.

Still, it is good that we live in the information age! You can quickly share their experiences, and get the big picture scene.>>

[Chris Peterson]

so...a higher point of explosion would mean occurring in a less dense part of the atmosphere. I assumed it was all about atmospheric pressure. If it is also heat buildup, why wouldn't it still happen at the same point? A flatter trajectory is longer, but through thinner air, on average, so heat would build more slowly than on a steep descent - still confused! thanks.

A flat trajectory allows more time for the meteoroid to slow down, while still in somewhat thinner air. This allows it to descend deeper into the atmosphere. The disruption isn't related to the heat buildup- there is none. It is related to the pressure exerted on the face of the body as it compresses air in front of it, and that is determined not just by the atmospheric density, but by the speed of the body as well.

During showers, when I have many events on my cameras, I see a very clear correlation between angle of descent and the height the meteor ends, with steeper angled bodies burning up higher.

[LocalColor]

Congratulations Marat Ahmetvaleev for capturing this great image!

[MargaritaMc]

I thought these later photographs were pretty stunning

Click to view full size image

Click to view full size image

http://marateaman.livejournal.com/27910.html
How amazingly quick-witted he was, to get all these unbelievable images when he had been anticipating a quiet morning photographing the frost on trees...

Margarita

[Stendec]

Apparently the folks in Chelyabinsk are quite fortunate that the meteor did not explode at an altitude lower than 12 - 18 miles (20 - 30 Kilometers). The explosive force of 500 kilotons is very much more powerful than the bombs which fell on Hiroshima (16 kilotons) and Nagasaki (21 kilotons) - - 31.25 times and 23.81 times more powerful, respectively. The bombs exploded less than half a mile above the ground (Hiroshima - detonation height about 1,968 feet; Nagasaki - detonation height about 1,539 feet). For comparison, look at the before and after pictures of Hiroshima and Nagasaki, and then do some mental extrapolation: http://en.wikipedia.org/wiki/Atomic_bom ... d_Nagasaki