How much light-gathering ability needed?

[misterrachel]

Just curious how much light-gathering ability a space (or earth) - based telescope would need to be able to directly image an extrasolar planet? Is this even within the realm of possibility?

 

[najab]

It's not raw light gathering that's needed in this age of super-sensitive CCDs, it's aperture - that's where interferometers come in. All the plans I've seend for terrestrial-class planet finding telescopes use a flotilla of space-based telescopes.