Searching for exoplanets around Alpha Centauri
Apparently it is the equivalent of looking for a bacterium one meter from
a grain of sand at a distance of ten kilometers:
http://seedmagazine.com/content/article/the_long_shot/P1/
Some of those big space telescopes they have on those proverbial
drawing boards could find a lot of Earth-type worlds and apparently
even image any continents on them.