Comet 8P Tuttle.
 
 Comet 8P Tuttle was first observed in 1790 and has returned every 13.6 years since. However, the latest apparition of this regular visitor has been one of the best. This image was shot on new years eve 2007, just 24 hours prior to its closest approach to Earth. Cyanogen, a poisonous gas & diatomic carbon (C₂) are present in the comet's atmosphere, both of which glow green when exposed to UV sunlight. The smudge at lower right is a spiral galaxy, M33. Photo details: Canon 350D, ISO 1600, 55 second exposure with a Canon EF-135mm lens @ f-3.5.

 Image taken December 31st 2007