Wednesday, May 21, 2008
How can the impact of a meteor or other cosmic object make an explosion on the Moon without oxygen present? It turns out NASA scientists have had to ask themselves that a lot, and they think they've come up with a solution. Some 100 lunar flashes have been observed over the past two and half years, leading to scientific study of a phenomenon once dismissed as imaginary. Bill Cooke of Marshall Space Flight Center explains that it has to do with the velocities - up to 30,000 mph - with which objects strike the lunar surface (given that there's no atmosphere to slow them down). "At that speed, even a pebble can blast a crater several feet wide. The impact heats up rocks and soil on the lunar surface hot enough to glow like molten lava — hence the flash."