Was the Chelyabinsk meteor relativistic? (split from napkin at speed of light)

[michel123456]

The situation is slightly different, but Randall Munroe does a pretty thorough job of explaining what would happen of you threw a baseball near relativistic speeds. The bulk of this would still be true for a napkin.

 

https://what-if.xkcd.com/1/

Woaw.

Doesn't that description fits with the Chelyabinsk meteor explosion?

[pavelcherepan]

Thanks swansont! That was an exciting read!

 

Woaw.

Doesn't that description fits with the Chelyabinsk meteor explosion?

 

Not really. The meteor was moving at some 25 km/s, about 0.01% of the speed of light, way too slow for the article description to apply.

 

What happened there was that the meteor entered dense atmosphere moving at hypersonic speeds and then rapidly slowed down due to interaction with air and excess kinetic energy was turned into heat.

[Janus]

Woaw.

Doesn't that description fits with the Chelyabinsk meteor explosion?

No. The meteor was moving at much less than any appreciable fraction of c, did not cause any fusion in the air particles it collided with, or produce any hard radiation in the form of x-rays or gamma rays.

[michel123456]

No. The meteor was moving at much less than any appreciable fraction of c, did not cause any fusion in the air particles it collided with, or produce any hard radiation in the form of x-rays or gamma rays.

There was plasma

 

from Wiki

 

 

Common forms of plasma

Artificially produced

 

 

The area in front of a spacecraft's heat shield during re-entry into the atmosphere

 

And there was an explosion.

 

From here

On account of its high velocity and shallow angle of atmospheric entry, the object exploded in an air burst over Chelyabinsk Oblast, at a height of around 29.7 km (18.4 miles, 97,400 feet).^[7][8] The explosion generated a bright flash, producing a hot cloud of dust and gas that penetrated to 26.2 km, and many surviving small fragmentary meteorites, as well as a large shock wave. The majority of the object's energy was absorbed by the atmosphere, with a total kinetic energy before atmospheric impact equivalent to approximately 500 kilotons of TNT (about 1.8 PJ), 20–30 times more energy than was released from the atomic bomb detonated at Hiroshima.

 

20–30 times more energy than was released from the atomic bomb detonated at Hiroshima.

 

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What is the formula that gives the explosion point for an object of mass M entering the atmosphere at velocity V?

[pavelcherepan]

What is the formula that gives the explosion point for an object of mass M entering the atmosphere at velocity V?

 

I don't know the formula but here's a link to a program developed by the guys from Purdue University. I entered parameters similar to what is known about Chelyabinsk meteorite and got similar results. UPDATE: Here's a link to their paper that the program is based on. Formulas are all there:

 

http://www.purdue.edu/impactearth/Content/pdf/Documentation.pdf

 

It's only the air burst energy that came way lower than NASA estimates.

 

 

 

The projectile begins to breakup at an altitude of 55600 meters = 182000 ft

The projectile bursts into a cloud of fragments at an altitude of 32600 meters = 107000 ft.

The residual velocity of the projectile fragments after the burst is 15.8 km/s = 9.82 miles/s.

The energy of the airburst is 9.73 x 10^14 Joules = 0.23 x 10^0 MegaTons.

No crater is formed, although large fragments may strike the surface.

Edited March 22, 2015 by pavelcherepan

[michel123456]

As the impactor penetrates the atmosphere the atmospheric density increases and the stagnation pressure at the leading edge of the impactor rises. Eventually, this exceeds the strength of the impactor, and it begins to break up. Observed meteoroids often undergo several cascades of breakup, reflecting components of widely varying strengths.

 

There is no mention of plasma here. the process is depicted as a pressure thing. although I thought that the explosion of the meteor was a result of plasma burst.

 

Edited March 22, 2015 by michel123456

[John Cuthber]

A candle flame is a (weak) plasma. What has plasma got to do with the question?

Admittedly, a snail experiences time dilation due to his speed; relativistic effects don't suddenly switch on at some velocity.

But the relativistic effects of that meteor will be tiny.

[michel123456]

A candle flame is a (weak) plasma. What has plasma got to do with the question?

Admittedly, a snail experiences time dilation due to his speed; relativistic effects don't suddenly switch on at some velocity.

But the relativistic effects of that meteor will be tiny.

So you say the meteor air burst was not caused by a plasma explosion?

From the link above

 

The ideas of aerodynamics don’t apply here. Normally, air would flow around anything moving through it. But the air molecules in front of this ball don’t have time to be jostled out of the way. The ball smacks into them so hard that the atoms in the air molecules actually fuse with the atoms in the ball’s surface. Each collision releases a burst of gamma rays and scattered particles.

These gamma rays and debris expand outward in a bubble centered on the pitcher’s mound. They start to tear apart the molecules in the air, ripping the electrons from the nuclei and turning the air in the stadium into an expanding bubble of incandescent plasma.

[John Cuthber]

The burst was definitely not due to fusion- there's just not an adequate energy density to provoke that.

It's quite a challenge to get what most people would recognise as an explosion without plasma. Anything much more energetic than a burst tyre is going to make plasma.

What do you think the phrase "a plasma explosion" means?

[michel123456]

The burst was definitely not due to fusion- there's just not an adequate energy density to provoke that.

It's quite a challenge to get what most people would recognise as an explosion without plasma. Anything much more energetic than a burst tyre is going to make plasma.

What do you think the phrase "a plasma explosion" means?

Well, i think plasma formed in front of the comet in the form of burning air, flames.

Then it exploded. Bam.

As in the picture below

http://static.guim.co.uk/sys-images/Guardian/Pix/pictures/2013/9/15/1379253210439/Chelyabinsk-meteor-008.jpg

[swansont]

There are many ways of forming a plasma. You can do it with a grape in your microwave oven. Relativistic speeds need not be present.

[michel123456]

There are many ways of forming a plasma. You can do it with a grape in your microwave oven. Relativistic speeds need not be present.

Right.

My question was about plasma, not about relativistic velocity.

I find it remarkable that the comet described a burning path, then suddenly exploded, and especially that the explosion looks centered on a point and not elongated along the path.

So it looks like a phenomena occured: the desintegration of the comet. But a desintegration would not necessary produce a bright flash. If I hit violently a stone with a hammer, the stone will eventually break in pieces but no flash will be produced. I think the flash originated in the exploding plasma and that the exploding plasma is the cause of the desintegration of the comet.

[pavelcherepan]

Right.

My question was about plasma, not about relativistic velocity.

I find it remarkable that the comet described a burning path, then suddenly exploded, and especially that the explosion looks centered on a point and not elongated along the path.

So it looks like a phenomena occured: the desintegration of the comet. But a desintegration would not necessary produce a bright flash. If I hit violently a stone with a hammer, the stone will eventually break in pieces but no flash will be produced. I think the flash originated in the exploding plasma and that the exploding plasma is the cause of the desintegration of the comet.

 

NASA site has some explanations to that regard: http://neo.jpl.nasa.gov/news/fireball_130301.html

 

As far as disintegration is concerned, same NASA website and the article I linked earlier (from page 819) have some descriptions of what causes it and how it happens.

 

P.S. It's not a comet but is usually referred to as meteor or 'superbolide meteor'. On a side note - Ain't it strange by the way? Pieces of it did land on the surface, so why meteor? Why not meteorite?

Edited March 23, 2015 by pavelcherepan