spacetoday.net: Astronomers estimate more planets than stars in our galaxy

Posted: Thu, Jan 12, 2012, 8:41 AM ET (1341 GMT)
Exoplanet abundance illustration (ESO)

The number of planets in our galaxy likely exceeds the number of stars, putting the total number of worlds at over 100 billion, astronomers reported Wednesday. An international team of astronomers used a technique called gravitational microlensing, where the gravity of a star and any planets act like a lens, magnifying the light of a background star. Microlensing search efforts have detected several planets in recent years, allowing scientists to calculate statistics on the likelihood of extrasolar planets. By their calculations, one of six stars studied have Jupiter-sized planets, half have Neptune-sized planets, and two-thirds have so-called "super-Earth" terrestrial planets. Combining these statistics lead astronomers to conclude that the average number of planets per star is more than one, meaning there is over 100 billion planets in our galaxy.