# Meteorite fall in Chelyabinsk!

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They were cold because they had just been cooled down by passing (relatively slowly) through the rather cold Russian atmosphere.

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Have you ever gone primitive camping? If you have, you should know that you don't use sedimentary rocks such as sandstone for the fire ring because if you do they might explode. Combustion is not need

Today registered a decline metiarita! Flash seen for 300 miles! Does not work mobile. There are wounded from cuts of broken glass! The evening will fly folder, NASA will be broadcast live!   Here is

Wondering how quickly this event will get political. The far righty are always accusing the scientific community of sensationalism. They want to defund Nasa because they have provided evidence which

Meteorites are often cold when they hit the ground, sometimes hoar frost will from an a meteorite soon after it lands if the air is moist. Some say it's because they loose their heat in the atmosphere others say they are cold while in space and do not heat up significantly as they pass through the atmosphere.

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"The meteor that crashed to earth in Russia was about 55 feet in diameter, weighed around 10,000 tons and was made from a stony material, scientists said, making it the largest such object to hit the Earth in more than a century."

I also heard it was traveling 18 miles per second before hitting the atmosphere and it exploded about 6 miles high, 30 times the energy of the Hiroshima atomic bomb, and yet smaller than the Tunguska explosion of 1908.

Edited by Airbrush
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I'd add: the biggest publicly known since Tunguska. Because this huge event would pass unnoticed over the Pacific, the Southern Atlantic, the Antarctic, and many more locations. An other meteorite crashed over central Cuba one day before or after and nobody knows even its path.

Surveillance networks exist for infra-sound (initially to detect aerial nuclear explosions) and for earthquakes, but these networks don't use to go public for an event that would be minor if away from a city.

Over the southern Pacific one unexplained event made the loudest noise observed to date. A meteorite is one possible explanation, then it would have been big.

I'm a bit wary about the 18 miles/sec. Russians give lower figures, like 18 km/s. Wait and see what they tell. Nor did the object explode at one precise altitude; much more, it lost matter over the whole atmospheric path, and some quick big parts reached the ground.

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I do find that fascinating though that this bit of "rock" transferred considerably more energy to the atmosphere than the nuclear weapons we designed to explode with huge force. Just imagine if a Tunguska like event just so happened to occur directly over a major city, the consequences would be devastating - it would be tantamount to setting off a hydrogen bomb mid-air over said city.

Extraordinary, for all our advances in technology and the supposed anti-missile systems which cover countries like the US - if one of these bits of "rock" penetrated our atmosphere and headed straight for a major city, there'd be nothing we could do to stop it in time.

It's also interesting to note the key reason why the energy released from these objects is so high - the kinetic energy (classically) of a body is Ek = 1/2 mv^2, so it is clear to see here that v will have much more of an impact of the kinetic energy of the body than its mass.

Suppose, for example, that we were able to accelerate a measly 1kg mass up to the 99% of the speed of light and then get this mass to impact a body - I'm fairly sure that the relativistic kinetic energy is given by

$E_k = (\gamma - 1)m_0 c^2$

where gamma is the Lorentz factor and m0 is the rest mass - we are assuming that the mass will remain constant at 1kg, which it will not but just for simplicity we'll make such an assumption.

Plugging in the values, we get that

$E_k \approx 5.4\times 10^{17}\, J$

which is around 130MT of TNT equivalent, or 2.6x the energy of the most explosive nuclear weapon ever tested which was Tsar Bomba which exploded with an energy of 50MT TNT equivalent.

In other words, this simple 1kg mass would be the deadliest, most destructive weapon developed by man if we could achieve that kind of speed - which, by the way, is extremely unlikely and entirely unfeasible as well as it would take a huge amount of energy to accelerate the mass to such a speed anyway!

Anyway, that's enough of my ramblings...

Edited by x(x-y)
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Moderator Note

Similar threads merged. Let's stay on-topic.

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Thank you Moontanman, at last some info. Great post!

Under "light & sound effects during flight" (P53) - read it on the link (Ididn't want to break the copyright by posting the excerpt here)

No mention about the Flash although.

"The meteor that crashed to earth in Russia was about 55 feet in diameter, weighed around 10,000 tons and was made from a stony material, scientists said, making it the largest such object to hit the Earth in more than a century."

I also heard it was traveling 18 miles per second before hitting the atmosphere and it exploded about 6 miles high, 30 times the energy of the Hiroshima atomic bomb, and yet smaller than the Tunguska explosion of 1908.

http://online.wsj.com/article/SB10001424127887323764804578312264130040432.html

As I mentioned above, Russian source estimates the weight as 10 tonnes, not 10,000 tons see post #45 . The discrepancy is of 10^3 order.

the wiki article is kept up-to-date constantly.

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As I mentioned above, Russian source estimates the weight as 10 tonnes, not 10,000 tons see post #45 . The discrepancy is of 10^3 order.

You got that first number from wikipedia, which in turn got it from various British press sources, which in turn got it from ... where? The answer is that for the most part, they got it from each other. The news media don't do much independent journalism nowadays. One outlet might do a smattering of independent journalism, screwing up somewhere along the line. Then they'll sell that messed up story to other outlets.

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Basically the russian (?) number is spread over by the greek media here. I'll have to check out.

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That number (10 tons, metric or English, it doesn't matter) is just wrong. Meteoroids that small hit the Earth's atmosphere multiple times per year. They don't cause the kind of damage, let alone the brightness, that this one did.

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This so far from the guardian

12.22pm GMT

The Associated Press has a statement on the meteor from the Russian Academy of Sciences.

The academy says the meteor weighed 10 tons and entered the earth’s

atmosphere at a speed of at least 33,000mph (54,000kph) and shattered

between 18 and 32 miles above ground (30 to 50km).

Digging in progress
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Here's the original source for that 10 ton figure: http://www.ras.ru/news/shownews.aspx?id=1da2959b-902f-46b2-9f1f-0c62d19740e8

This might have been a preliminary estimate, or they might have intentionally downplayed the event. In any case, it's wrong. A ten ton meteor is not going to cause near as large a shock wave as the one that did occur, not is it going to register on seismic stations worldwide, or on nuclear test ban monitoring systems as far away as Australia.

Edited by D H
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Thanks, you are fast.

So the difference is between a (russian) object of roughly 2 meters diameter and a (american) object of roughly 20 metres diameter. A falling SUV against a falling 6 floor building, both full of concrete.

Edited by michel123456
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Thanks, you are fast.

So the difference is between a (russian) object of roughly 2 meters diameter and a (american) object of roughly 20 metres diameter. A falling SUV against a falling 6 floor building, both full of concrete.

everything is bigger in America...

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Here's the original source for that 10 ton figure: http://www.ras.ru/news/shownews.aspx?id=1da2959b-902f-46b2-9f1f-0c62d19740e8

This might have been a preliminary estimate, or they might have intentionally downplayed the event. In any case, it's wrong. A ten ton meteor is not going to cause near as large a shock wave as the one that did occur, not is it going to register on seismic stations worldwide, or on nuclear test ban monitoring systems as far away as Australia.

I do lean towards agreeing with you about the weight. But, along those lines, would the material the meteorid was made of effect the flash or the shockwave? Don't know about the shockwave, but say the meteorid contained a lot of, say, magnesium and be relatively light. Could it produce a fireball as big as a larger rock meteorid, for example?

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the object is not made of fuel. It is not a flaming aircraft. It is a rock. it can burn like lava but the main thing that is burning is the atmosphere. When a spacecraft enters the atmosphere, what is burning in front of the protection shield?

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I do lean towards agreeing with you about the weight. But, along those lines, would the material the meteorid was made of effect the flash or the shockwave? Don't know about the shockwave, but say the meteorid contained a lot of, say, magnesium and be relatively light. Could it produce a fireball as big as a larger rock meteorid, for example?

Unless it was native (elemental) magnesium that would not have been a factor, pure magnesium is about as likely as pure oxygen in that context..

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Unless it was native (elemental) magnesium that would not have been a factor, pure magnesium is about as likely as pure oxygen in that context..

Oh, I didn't mean this one was high on magnesium. Was rather thinking of space rocks in general. Thanks for the info! Will read up on elemental magnesium, never heard the expression before.

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Moderator Note

Posts arguing that the Meteor was shot down by a UFO have been split off to Speculations. Let's keep this science please.

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The lesson to learn is that when you see a bright flash in the sky, GET AWAY FROM WINDOWS! Or you will have glass shards in your face and eyes.

If I noticed such a flash, I confess I would have gazed out the window at it for several minutes, just long enough to get seriously injured. I wonder how many of over 1,000 injured were blinded for life?

A report said the shock wave arrived "a couple minutes" after the flash. If the shock wave traveled at the speed of sound (approx 768mph) then 2 minutes would indicate the blast took place about 24 miles away.

Edited by Airbrush
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In other words, this simple 1kg mass would be the deadliest, most destructive weapon developed by man if we could achieve that kind of speed - which, by the way, is extremely unlikely and entirely unfeasible as well as it would take a huge amount of energy to accelerate the mass to such a speed anyway!

Anyway, that's enough of my ramblings...

I enjoyed your post. Interesting notion.

Forget the 1 kg object. Let's think about the recent Chelyabinsk meteorite! I wonder what devastation that would cause if it was traveling at relativistically high speeds (not necessarily 0.99c but something reasonably high for cosmological phenomena).

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That's a good question. Just how fast can a meteor or comet impact Earth? I would think it would be a comet orbiting the Sun in the opposite direction. How fast could that be? Halley's comet was moving 43 miles per second as it passed Earth.

Probably the highest speed an object can be moving, relative to Earth, would be a high velocity neutron star 600 miles per second. At several solar masses, and only 12 miles wide, would it punch a hole thru the Earth and keep going leaving the Earth behind? Or would it drag the Earth along with it and completely absorb the Earth?

Getting back to the recent Russian meteor impact, that was an extraordinary event, once in a hundred years, plus or minus a few decades. There could have been such a 30-Hiroshimas-bomb blast over the ocean or a desolate area, and the nearest human thought it was just lightning and thunder, especially if it impacted in the early 20th century, such as the Brazilian blast of 8-13-1930 which was between 0.1 and 5.0 megatons of TNT.

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

http://apod.nasa.gov/diamond_jubilee/papers/lamb/node3.html

Edited by Airbrush
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(...)

In other words, this simple 1kg mass would be the deadliest, most destructive weapon developed by man if we could achieve that kind of speed - which, by the way, is extremely unlikely and entirely unfeasible as well as it would take a huge amount of energy to accelerate the mass to such a speed anyway!

Anyway, that's enough of my ramblings...

So far we (you) have achieved mach25 for a 100 tonnes object.

That is 8200 m/s to be compared to the estimated 15000 m/s atmospheric entry of the russian meteor.

Edited by michel123456
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That's a good question. Just how fast can a meteor or comet impact Earth? I would think it would be a comet orbiting the Sun in the opposite direction. How fast could that be? Halley's comet was moving 43 miles per second as it passed Earth.

Probably the highest speed an object can be moving, relative to Earth, would be a high velocity neutron star 600 miles per second. At several solar masses, and only 12 miles wide, would it punch a hole thru the Earth and keep going leaving the Earth behind? Or would it drag the Earth along with it and completely absorb the Earth?

Getting back to the recent Russian meteor impact, that was an extraordinary event, once in a hundred years, plus or minus a few decades. There could have been such a 30-Hiroshimas-bomb blast over the ocean or a desolate area, and the nearest human thought it was just lightning and thunder, especially if it impacted in the early 20th century, such as the Brazilian blast of 8-13-1930 which was between 0.1 and 5.0 megatons of TNT.

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

http://apod.nasa.gov/diamond_jubilee/papers/lamb/node3.html

I thought Tunguska level events were once in a hundred years but your link would suggest this is not the case. Your link suggests a 1 kilometer crater from the Brazilian event. But the specific wiki page doesn't mention a crater.

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

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Wow, so that might be what it looks like to see a hyper velocity neutron star, punching thru Earth? Not quite, a neutron star at 12 miles across is VERY tiny compared to an 8,000 mile wide Earth. It would be a tiny dot with a thin tail (or how thick a tail could it create?) of Earth material following it. It would go thru Earth like a bullet thru a cloud. But nice poster, never-the-less. Thanks for posting that mountainman.

Last I heard, Tunguska level events were every few hundred years for a meteor 50 YARDS across. The recent Siberian blast of 2-15-13 was said to happen once in a hundred years, and it is only 50 feet across.

Edited by Airbrush

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