Thanks. Very informative. I had suspected that light refraction would play a key role in this, but I didn't realize that we could get such a wealth of detail. So, it appears that we'd be able to break down the composition of a planet's atmoshphere merely by studying how light refracts off it.
And you say we'll have planet-seeing telescopes in space... But will we get actual pictures, or computer constructs based on the data?
We don't get actual photographic pictures any more, not with the big scopes. It's all sensors acquiring data in spectral bands. There is simply too much data coming to be all analyzed anymore, so much of it is being made available on the Internet for anyone so disposed to take a crack at it.
The planet-finder telescopes in space will be new technology arrays. There would be no way to get a photographic picture since the data will have to pass through various mathematical filters in order to make anything recognizable.