As far as NASA is concerned, an object needs to transit its star three times before they’ll consider it a candidate for planetary status. Then comes a lengthy process of calculations and secondary measurements to make the confirmation.
Luckily, the field is still ripe for finding the first true analog of Earth. So if you have ambitions in that direction, there are a few things you can search for among Kepler’s gatherings:
It needs to be the right mass and size for the planet to be a rocky world.
It need to orbit in the so-called Goldilocks zone of its star—just the right distance for the star’s heat to support liquid water on the surface.
It shouldn’t be tidally locked, or one side will always face the star, creating a world that’s half red-hot melted, half frozen wasteland.
The star should be relatively quiet, or massive solar flares will wipe away any protective ozone and fry chances for surface life.
And that’s just the stuff that Kepler can help us determine about a given planet. At the distances involved, the probe can’t tell you if an alien world has a magnetic field, a decent atmosphere, actual water bodies, and a dearth of ravenous bugblatter beasts.