Its discovery proved that the Kepler spacecraft, which was launched in March 2009, could indeed do what its designers had boldly
promised: find small, Earth - size
planets around distant
stars, a task that once seemed so difficult as to border on the absurd.
We're looking at extrasolar
planets [ones
around other
stars], but there are also a bunch of places in our solar system that look
promising — the moons of Jupiter and Saturn, and back again to Mars.