sciencehabit writes: A fluorescent glow high in the atmosphere of Titan, Saturn's largest moon, signifies the presence of a gas that astronomers have yet to identify. The glow appears only on the daytime side of the moon at altitudes between 600 and 1250 kilometers, with the largest intensity occurring at an altitude of about 950 km. Detailed analyses reveal that the glow doesn't stem from a problem with the Saturn-orbiting Cassini craft, and it isn't associated with methane or any of the other hydrocarbons already identified as constituents of Titan's atmosphere.
The F-15 Eagle:
If it's up, we'll shoot it down. If it's down, we'll blow it up.
-- A McDonnel-Douglas ad from a few years ago