Today, NASA will hold a press conference discussing the most recent discoveries of the Kepler Observatoty.
The Kepler space telescope is watching 156,000 stars for signs of planets. When the planet crosses in front of the star (relative to the earth) it eclipses the starr andd the star dims a bit. Kepler can sense this.
When the planet goes behind the star then the star blocks the reflected light from the planet. Kepler can sense this.
Within the next three years, if Kepler continues to function, it will almost certainly discover a number of earth-sized planets in earth-type orbits around sun-like stars.
It can even tell if the planets have large moons.
By spectoscopic analysis of starlight passing through the planet's atmosphere, we can tell it's chemical composition.
Nitrogen and oxygen - with small amounts of carbon dioxide, water, and methane - that will tell us something.
A planet with life orbiting another star.
It could very well happen in the next three years.
So, the news is that Kepler has found 54 planet candidates in the habitable zones of their respective stars. Of these, 5 are earth-size, and many of the rest are capable of having moons that are earth-sized or, at least, large enough to have an atmosphere and liquid water.
Further research is required to confirm that these are planets and to determine more specifically their properties.