Titanglow

Scientists working with images from the Cassini spacecraft have discovered that Saturn's huge moon Titan gives off the tiniest bit of a glow.  They weren't surprised by a glow high in Titan's atmosphere-- molecules there can be excited by solar radiation and emit light-- but the glow also comes from deep down in Titan's thick atmosphere.

Exactly what is exciting molecules down there where solar radiation is not really a factor is unclear.  It is clear, however, that Titan is still full of surprises.