Comet C/2007 Q3 (Siding Spring) made its closest approach
to the sun on October 7, 2009. Even then, its distance from
the sun (200 million miles) was still about twice the average
earth-sun distance. The comet was also about that distance
from earth at the time. The light from the comet took 18 minutes
to reach us. But the amazing size of the universe can be glimpsed
by realizing that light from the brightest galaxy in this picture
(NGC 4216) takes 40 million years to get to earth!

Image data:
Camera: SBIG ST-4000XCM
Exposure: 10 minutes x 7 (interrupted by dawn)
Telescope: 10" Schmidt-Newtonian, Baader MPCC