How Many Planets are Out There?

Four years ago a dedicated space telescope ("Kepler") was launched to search for terrestrial planets around other stars, and even possibly discover a planet that might be like the Earth. The main purpose of the mission is to find out how common planets are out to the distance we are from our Sun. I explain how the mission works, and highlight some of its most amazing discoveries. Nearly 3000 potential planets have been found, including many in multiple planet systems. The most common planet may be something that we don't have in our own Solar System: "super-Earths" which are 1.5-3 times as big as our planet. Some of these may be rocky, some may be "water worlds", and some may be more like warm Neptunes. The Kepler mission is rapidly leading us to the conclusion that most stars have planets going around them, and the number of earth-sized planets in our Galaxy is probably in the billions.

Speaker: Gibor Basri, UC Berkeley