Planet
The smallest known planet is PSR B1257+12A, one of the first extrasolar planets discovered, which was found in 1992 in orbit around a pulsar. Its mass is roughly half that of the planet Mercury. The smallest known planet orbiting a main-sequence star other than the Sun is Kepler-37b, with a mass (and radius) slightly higher than that of the Moon.
Draco (constellation)
The constellation contains the star recently named Kepler-10, which has been confirmed to be orbited by Kepler-10b, the smallest rocky Earth-sized planet yet detected outside of the Solar System.