[margalabargala]

PSA: The word "explosion" has multiple definitions, plenty of which are actually quite reasonable to apply to meteors! It can refer to the sound alone, for example. The people reporting an explosion in Massachusetts were not incorrect!

It would however, be incorrect to claim that the meteor had noting to do with explosions.

[jagged-chisel]

None of the definitions I found are concerned with only sound. One mentions sound as a result of an explosion.

PSA: expressing an opinion (incorrect or otherwise) is not actually a public service announcement

[jojobas]

No? There is no violent expansion or bursting, even if the sound is similar. It is as much an explosion as a supersonic jet passing by, and that is not much.

The term makes people think atmospheric heating causes an actual steam explosion and that's the source of shockwave, which can't be further from truth.

[bmelton]

Meteor Chelyabinsk suffered catastrophic fragmentation, a rapid, violent release of energy accompanied by a pressure wave with debris, which would satisfy the definition of an explosion (an in fact the energy released was equivalent to 400-500 kilotons of TNT.)

[jojobas]

If you could look at this catastrophic fragmentation you'd find it's about the same pace as dirt spreading on the ground as it gets tipped off a dump truck. The fragments outward speed is negligible compared with their forwards speed, and it's the forward speed that produces the shockwave, fragmented or not.

[sholladay]

Do you not consider Tunguska an explosion? It’s always described as such. IIRC, it never even hit the ground. Sure, a lot of the damage was caused by the air being compressed from above, but it created an air burst, which would have released a lot of energy in every direction.

[jojobas]

No, it's a misnomer as with any other meteor.

If you were to witness the breakup from the bolide's reference frame and without all the rushing air you'd never call it an explosion.

[margalabargala]

> and without all the rushing air

That's the exploding bit though. You don't need containment, you just need the the airburst. A hyper-heated pocket of air that then expands rapidly is itself an explosion.

[jojobas]

>then expands rapidly

Except it doesn't. The breakup has roughly the same dynamics as dirt spreading as it gets out of a tip truck. The shockwave is not produced by the outward motion, it barely has any speed.

[margalabargala]

You're conflating the outward motion of the rock with the outward motion of the air.

The shockwave is traveling at the speed of sound.