50bn planets in Milky Way, estimates first cosmic censusBy ANI
Monday, February 21, 2011
LONDON - The first cosmic census of planets in our galaxy has suggested that there are at least 50 billion planets in the Milky Way.
And some 500 million of those planets are in what is known as the Goldilocks zone, where the climate is thought to be not-too-hot and not-too-cold, and life could exist, reports the Daily Mail.
The numbers have been extrapolated from the early results of NASA’s Kepler telescope, almost two years though a three-and-a-half year mission.
Kepler science chief William Borucki said 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. Kepler spots planets as they pass between Earth and the star it orbits.
The mission found that 10.5 per cent of the stars in the sample are predicted to have Earth-size planets.
s many as 20.8 per cent should have Neptune-sized planets while 5.2 per cent should have Jupiter-scale planets, found the scientists.
Borucki and colleagues figured one of two stars has planets and one of 200 stars has planets in the habitable zone.
And that’s a minimum because these stars can have more than one planet and Kepler has yet to get a long enough glimpse to see planets that are further out from the star, like Earth, said Borucki.
To get the estimate for the total number of planets, scientists then took the frequency observed already and applied it to the number of stars in the Milky Way.
For many years scientists figured there were 100 billion stars in the Milky Way, but in 2010 a Yale scientist figured the number was closer to 300 billion stars.he findings were discussed at the American Association for the Advancement of Science annual conference in Washington. (ANI)