Richard Fangnail wrote:
A fast-moving object like a meteorite compresses the air in front of
it, causing heat. Does an ordinary plane have a problem with this or
is it not moving fast enough?

The Siberian meteor of 1908 exploded in midair. Why do you suppose it
did, as opposed to hitting the earth?

The object (either a stony asteroid or a small cometary nucleus--there are
models of both concepts to explain Tunguska) entered the atmosphere at a
speed estimated to be around 10 km/sec or more. That's fast--it would take
only a few seconds to pass from space through the upper atmosphere to the
altitude where it exploded, depending on the exact angle of descent and
speed. The ram pressure rapidly built up to the point where the object
exploded (from a shock wave propagating into the solid body--in effect, the
air in front of it was so compressed it exerted a force similar to that of
hitting a solid surface, and that air was extremely hot from the
compression). Most of the remaining kinetic energy turned into heat very
quickly (microsecs), resulting in a fireball similar to a thermonuclear
explosion. The shockwave from that explosion resulted in the damage and
sound effects observed on the surface.

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

Estimates vary, but it is thought to have been around 60 metres across.

--
Mike Dworetsky

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