NASA’s Kepler mission scientists have discovered a new planetary system that is home to the smallest planet yet found around a star similar to our sun. The planets are located in a system called Kepler-37, about 210 light-years from Earth in the constellation Lyra (the general direction of the star Vega). The smallest planet, Kepler-37b, is slightly larger than our moon, measuring about one-third the size of Earth. It is smaller than Mercury, which made its detection a significant challenge.