Lunar Flash Mystery Solved: Moon Just Passing Gas

Changes in the brightness and color over small areas of the moon's surface, known as Transient Lunar Phenomena, or TLP, have been observed telescopically for hundreds of years

Using data from decades-old observations, Crotts and colleagues have now found a strong correlation between TLP sightings and regions where lunar orbiting spacecraft have detected gas leaking out from beneath the lunar surface.

"The areas selected consistently by TLP are the craters Aristarchus (in about 50 percent of sampled reports), Plato (about 15 percent) with Kepler, Copernicus, Tycho and Grimaldi all at the few percent level apiece," Crotts said.

"This data ties in with observations made by the Apollo 15 and Lunar Prospector spacecraft which detected the gas radon-222 twice at Aristarchus and also once at Kepler and Grimaldi.

http://www.space.com/scienceastronomy/070730_gassy_moon.html