When small meteors crash into the atmosphere, the force of entry heats the objects to scorching temperatures.
Most of these objects are no bigger than grains of sand and constantly barrage our atmosphere.
Bigger meteors will sometimes explode into bright fireballs when the pressure of air in front of them seeps into their cracks and pores.
Jay Melosh, a professor of planetary sciences at Purdue University, explained: “There’s a big gradient between high-pressure air in front of the meteor and the vacuum of air behind it.
“If the air can move through the passages in the meteorite, it can easily get inside and blow off pieces.”
source: express.co.uk