I was interested in learning more about the status of our scientific understanding and technological instruments regarding extra solar spectroscopy.
I am motivated by this almost 3 year old question/answer here at physics SE.
The composition of extra solar planet should be taken with a pinch of salt, the science is very new and uses instruments not designed for the task. Keep an eye out for new missions such as ECHO which might fly in the next 5 to 10 years...
Since it has been almost 3 years, can someone give an update on our current understanding on this subject? I am curious as to how accurate our measurements of the composition of planets and stars outside our solar system are. Also, what is the impact of our atmosphere? Are we able to tease out the effects of absorption by our own atmosphere in order to get a clean signal?