Searching for ET with Telescopes

In Star Trek the Enterprise always seems to be tripping over class M planets, but it might be possible to find small Earth like planets using a technique known as nulling interferometry and earth based observatories:

Telescope Tech Will Speed Search for Extraterrestrial Life

“The smallest rocky planet detected to date has around four times the mass of Earth. This planet, as well as most of the 300 exoplanets discovered to date, have been detected by the “wobble” or shift in the light spectrum of the star caused by the slight gravitational tug of the orbiting planet. Another planet-hunting method, called gravitational microlensing, takes advantage of the way the gravity of an exoplanet’s star bends and focuses the light from a more distant star like a lens. Small deviations in the light from the distant star indicate that a planet is orbiting the lensing star.

Nulling interferometry will surpass both of these strategies in the search for smaller, earth-like worlds that orbit their star at a distance — in the “habitable zone” — that could harbor life. The technique involves incredibly precise measurements of the position of a star, so that the minutest wobble caused by the gravity of an orbiting planet 100,000 times smaller can be detected.”