Originally posted by twhitehead
Not sure why you compare it to Hubble. Hubble is special for being outside the atmosphere not for having a large mirror (its not all that large).
I compare it so I can do an estimate of the res of the larger scopes. For instance, Keck II uses adoptive optics and has some very high res images of the center of the galaxy letting them chart the course of stars around the central black hole, they have been doing that for 20 years and are looking for changes in orbits that would indicate holes in Relativity.
It uses a 10 meter dish, one fourth the size of this baby.
All things being equal, Hubble has about a 2 meter dish and clocks in at 0,05 arc seconds or so of res.
So I would expect Keck to have about 5 times that or 0.01 arc seconds and the new one at about 40 meters should clock in at 2.5 MILLIarcseconds of res. That will make for even sharper images of the central black hole region for just that one example.
But no matter what size Earth bound scopes are, 100 meter, whatever we come up with in the next 50 or 100 years, Hubble still has one advantage no Earth bound scope has, the ability to see IR and UV much better than anything that has to point through the atmosphere.
Of course the Webb scope will supersede Hubble in the IR band when it gets launched and if it works as planned. If it fails there is no quickie fix like Hubble getting all those repair runs via the Space Shuttle. And even now there is no quick fix to Hubble if it fails since we chucked the Shuttle.