In February 2013, NASA discovered a new planetary system that is home to the smallest known exoplanet, Kepler-37b. Like nearly all of the 3,000-plus confirmed or suspected exoplanets, it was discovered by the Kepler space telescope.

As part of NASA's Kepler mission, the Kepler space telescope has been in orbit around the sun since 2009. It does its work not by observing planets directly — they’re too far from Earth and too small for the telescope to see — but by detecting the slight dimming of starlight that takes place every time a planet transits, or passes in front of its star.

In this video, a NASA team talks about the Kepler mission to discover planets.