This artist's conception compares the KOI-961 planetary system to Jupiter and the largest four of its many moons. The KOI-961 planetary system hosts the three smallest planets known to orbit a star beyond our sun (called KOI-961.01, KOI-961.02 and KOI-961.03). The smallest of these planets, KOI-961.03, is about the same size as Mars. All three planets take less than two days to whip around their star.

The planets were discovered using data from NASA's Kepler mission and ground-based telescopes. The KOI-961 star is a tiny "red dwarf," just one-sixth the size of our sun. This planetary system is the most compact detected to date, with a scale closer to Jupiter and its moons than another star system.

The planet and moon orbits are drawn to the same scale. The sizes of the stars, planets and moons have been increased for visibility.

NASA's Ames Research Center in Moffett Field, Calif., manages Kepler's ground system development, mission operations and science data analysis. JPL managed the Kepler mission's development.

For more information about the Kepler mission visit http://www.nasa.gov/kepler.

Ball Aerospace and Technologies Corp. in Boulder, Colo., developed the Kepler flight system and supports mission operations with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.