Researchers at the California Institute of Technology used the data--combined with follow-up observations from the Palomar Observatory near San Diego and the W.M. Keck Observatory atop Mauna Kea in Hawaii--to discover three planets that are 0.78, 0.73 and 0.57 times the radius of the Earth orbiting a single star called KOI-961.
The smallest of the three--called "exoplanets" because they orbit stars--is about the size of Mars, according to NASA.
The newly discovered planets take less than two Earth days to orbit around their star, a red dwarf with a diameter one-sixth of the Sun, making it 70% larger than Jupiter.
The verification of the three planets follows several notable discoveries for Kepler in the last two months. In December, the mission identified the first planet in the habitable zone of a star like the Sun, Kepler-22b, which is 2.4 times the size of the Earth.
Later that month, the Kepler team also unveiled the discovery of the first planets the size of Earth orbiting a sun-like star outside our solar system--Kepler-20e and Kepler-20f.
