The orbiting Kepler observatory has been a remarkably successful project since its inception. By watching one small patch of the sky continuously, Kepler has enabled astronomers to discover upward of 2300 possible exoplanets—planets orbiting other stars. While many of those candidates likely are not actually planets, follow-up observations have confirmed 854 exoplanets as of December 28, 2012. The American Astronomical Society meeting, happening as I type this post, is devoting about 30% of its sessions to discussing recent exoplanet discoveries. This is an astoundingly rich field of study!

However, it’s also one that is remarkably accessible. Through the citizen science program Planet Hunters, non-scientists helped discover 42 planet candidates, 15 of which may lie in their system’s habitable zone—the region at which liquid water may exist on the surface.

The Planet Hunters identified 42 exoplanet candidates, including 33 with at least three transits—the more transits we can observe, the more reliable the identification as a planet, and the better the estimates of orbital characteristics. Forty of the potential exoplanets have orbits longer than 100 days, and 9 may have orbital periods greater than 400 days, placing them farther out than most previously identified worlds. [Read more…]