Fireball fragmentation
Fireball fragmentation is the breaking apart of a meteoroid in the air, often seen as sudden flares in brightness.
Most meteoroids that produce bright fireballs are not solid enough to survive intact. As they plunge deeper into denser air, the pressure on their front face rises until it exceeds the strength of the rock. They then break into fragments, each of which continues its own path. This fragmentation shows up as flares, when the sudden increase in surface area makes the fireball brighten.
Observations show that meteoroids often break at pressures much lower than the strength of meteorite samples, typically a few megapascals or less, because they are full of cracks. Many fireballs show several breaks in sequence, each at higher pressure, as weaker pieces fail first.
Fragmentation spreads meteorites over a strewn field, with the heaviest pieces carried furthest. Understanding it is important for predicting where meteorites land, and for estimating the damage from larger airbursts like Chelyabinsk, whose shock wave came largely from its rapid break-up between about 30 and 45 kilometres up.
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