Well, I think that the moon wouldn't be too feasible since it does rotate. If you land telescopes on the moon, you wouldn't be able to observe the sky for a lon

Well, I think that the moon wouldn't be too feasible since it does rotate. If you land telescopes on the moon, you wouldn't be able to observe the sky for a long period of time, like the hubble did with the deep field (50 days of time). It also doesn't make sense to geosync the telescope behind the "dark side" of the earth for the same reason. Long exposures wouldn't be easy since the earth does move around the sun, so the sky moves with it. Eventually you will have to face the sun to get the same shot of the sky. So, the only way would to be to have the orbit around the sun so the telescope can always face away from the sun. that way you can at least create the long exposures they need.