Quiz: Are you a space cadet or an Einstein?
-- Originally delayed by the Shuttle Challenger's tragedy, the Hubble telescope has given scientists a new way to look at the universe.
The Hubble has captured about 500,000 images of nearly 25,000 celestial objects.
Four service missions have helped prolong its life in orbit.
READERS: How did you score? What question would you have stumped others with?