The planet, nicknamed Xena after the warrior princess heroine of the television series, is about 20 percent larger than Pluto and 9 billion miles from the Sun, the London Telegraph reported Monday.
The moon, 100 times fainter than Xena and orbiting once every couple of weeks, was spotted Sept. 10 at the W.M. Keck Observatory, located at the summit of Hawaii's dormant Mauna Kea volcano, by Michael Brown of the California Institute of Technology. He, along with astronomers Chadwick Trujillo of the University of Hawaii and David Rabinovitz of Yale University, discovered Xena, the San Francisco Chronicle reported.
"Having a moon is something that most self-respecting planets have, so it is good to see that this one does too," Brown said.