Meteorites are hot when they land
Contrary to popular belief, meteorites are typically cold or room temperature when they reach the ground. The frictional heating of atmospheric entry is brief and affects only the outer surface, while the interior remains cold from the deep-space environment.
What we know
When a meteoroid enters Earth's atmosphere at speeds of 11 to 72 km/s, the compression and friction of air cause intense surface heating. This is the cause of the glowing fireball visible during a meteor event. However, this heating phase lasts only a few seconds, and the meteoroid is also decelerated by the atmosphere. By the time the object slows to subsonic speeds and stops glowing (a phase called dark flight), it may still be tens of kilometers above the ground.
During the dark flight phase, the still-cold interior of the meteoroid actually chills the outer surface through conduction. Washington University in St. Louis, which maintains a meteorite database, notes that meteorites do not burn and do not start fires. NASA spokesperson Bill Cooke has confirmed that meteorites are quite cold and can be picked up when they land.
The interior of a meteorite was in deep space at temperatures around -270 degrees Celsius (3 degrees above absolute zero) until very recently before impact. Heat conduction through stone or iron is slow, taking far longer than the brief atmospheric transit to raise the interior temperature significantly. The outer fusion crust formed by melting may cool rapidly once heating stops.
Eyewitness reports of meteorite falls consistently describe objects that are cool or warm to the touch rather than burning hot. Some meteorites have reportedly been found with frost on them shortly after landing, because the cold interior chilled surface moisture from the air.
Common claims
- Meteorites are too hot to touch when they landFalse - typically cool or cold
- Meteors glow because they are on fireFalse - glow is from atmospheric compression and friction
- Meteorites can start fires where they landNot supported - surface cools during dark flight