This photo of comet Lovejoy, C/2014 Q2 was taken on the evening of January 14, 2015. The original photo was a 60-second exposure in color, but to increase the visibility of the tail, I converted it to black and white. The tail points directly away from the sun, a result of light pressure on the ionized gas released from the comet.
Here is the corresponding color image. The green glow of the comet’s head results from fluorescing carbon atoms (C2) in ultraviolet light from the sun. For further explanation of the origin of the green color, visit the Planetary Society page. Camera was a Canon 6D on a Takahashi FSQ-106 at f/5.
Comet Lovejoy C/2014 Q2’s orbital period around the sun is roughly 11,500 years. If you miss it on this pass, it will return in about 8,000 years hence.