Saturday, January 21, 2012
An Abundance of Exoplanets Changes our Universe
Scientific American wrote An Abundance of Exoplanets Changes our Universe "About 17% of stars (give or take several percent) harbor Jupiter mass planets, cool Neptunes exist around about 52% of stars and Super-Earths (5 to 10 times the mass of Earth) exist around roughly 62% of stars. Even with sizable errors in these estimates (as much as 20-30%) the numbers are astonishing – there are at least 1.6 planets orbiting from 0.5 to 10 AU for every star in the galaxy. Combine this with the Doppler survey numbers (25% of stars with ‘Earth-sized’ planets within 0.25 AU), the Kepler numbers (17% of stars with ‘Neptunes’ orbiting within 0.5AU), and the microlensing estimates of 2 rogue giant planets per star in the galaxy and you have, well you have an awful lot of planets."