Scientists have estimated the first cosmic census of planets in our galaxy and the numbers are astronomical: at least 50 billion planets in the Milky Way.
At least 500 million of those planets are in the not-too-hot, not-too-cold zone where life could exist. The numbers were extrapolated from the early results of NASA's planet-hunting Kepler telescope.
Kepler science chief William Borucki says scientists took the number of planets they found in the first year of searching a small part of the night sky and then made an estimate on how likely stars are to have planets.
They figured one of two stars has planets and one of 200 stars has planets in the habitable zone.
There are at least 100 billion stars in the Milky Way.