In 1930, astronomers discovered Pluto. In 1978, astronomers discovered one moon, Charon, orbiting Pluto. Now astronomers have discovered two more natural satellites, or moons, orbiting Pluto. Marc Buie and his team at the Lowell Observatory studied eight-minute exposure images taken by Hubble Space Telescope in 2002. In May 2005, they identified two new moons orbiting Pluto. It’s the only quadruple system found in the Kuiper Belt.

The two moons’ orbits are about twice as far away from Pluto as Charon, but orbit in the same plane. The new moons are temporarily designated as S/2005 P1 and S/2005 P2. They are about 40,000 and 30,700 miles away from Pluto. Their magnitudes, a measure of brightness, are 23.1 and 23.4. Based on reflectivity similar to ordinary meteorites (rocks), their magnitudes indicate their size as 93 and 62 miles wide. Their orbital periods are 38 and 25.5 days long.

Scientists believe the moons were formed as a result of a high-energy collision that probably formed Pluto’s largest moon Charon too. The moons will be studied from Earth again in February, when Pluto moves out from behind the sun.

In January 2006, a new spacecraft will be launched on a mission to study Jupiter, Pluto, and the Kuiper Belt. The New Horizons mission will study Pluto and its triple moon system when it arrives there in July 2015.