Kepler's mission is "to discover Earth-like planets in Earth-like places — that is to say, in the not-too-cold, not-too-hot, Goldilocks zones around stars where liquid water can exist."
The job, in short, is to find places where life as we know it is possible.
Kepler, named after the German astronomer who in 1609 published laws of planetary motion that now bear his name, will look for tiny variations in starlight caused by planets passing in front of their stars. Dr. Borucki and his colleagues say that Kepler could find dozens of such planets — if they exist. The point is not to find any particular planet ... but to find out just how rare planets like Earth are in the cosmos.
“It really is going to count many Earths. About four years from now we will have a really good estimate of how many Earths there are.”
... if all keeps going well, it will be time to confront the next series of questions: whether anywhere else in this galaxy the dust that once spewed from stars has come alive and conscious.
“We are going to be able to answer for the first time a question that has been pondered since the time of the ancient Greeks. Are there other worlds like ours? The question has come down to us from 100 generations. We get to answer it.”
If Kepler doesn’t come through, that means Earth is really rare and we might be the only extant life in the universe and our loneliness is just beginning."
In a lonely cosmos, a hunt for worlds like ours