WASHINGTON, D.C. (BNO NEWS) — Astronomers from NASA discovered a fourth moon orbiting the icy dwarf planet Pluto, the agency said Wednesday.
Using the Hubble Space Telescope to search for rings around the dwarf planet, astronomers spotted the new moon, which is the smallest discovered around Pluto. It has an estimated diameter of 8 to 21 miles (13 to 34 kilometers) and was temporarily designated P4.
By comparison, Charon, Pluto’s largest moon, is 648 miles (1,043 kilometers) across, and the other moons, Nix and Hydra, are in the range of 20 to 70 miles in diameter (32 to 113 kilometers).
P4 was first seen in a photo taken with Hubble’s Wide Field Camera 3 on June 28. It was confirmed in subsequent Hubble pictures taken on July 3 and July 18. The moon was not seen in earlier Hubble images because the exposure times were shorter, NASA said. However, there is a chance it appeared as a very faint smudge in 2006 images, but was overlooked because it was obscured.
The new moon is located between the orbits of Nix and Hydra, which Hubble had previously discovered in 2005. Charon was discovered in 1978 at the U.S. Naval Observatory and first resolved using Hubble in 1990 as a separate body from Pluto.
The dwarf planet’s entire moon system is believed to have formed by a collision between Pluto and another planet-sized body early in the history of the solar system. The smashup flung material that coalesced into the family of satellites observed around Pluto.
“I find it remarkable that Hubble’s cameras enabled us to see such a tiny object so clearly from a distance of more than 3 billion miles (5 billion kilometers),” said Mark Showalter of the SETI Institute in Mountain View, California, who led this observing program with Hubble.
The finding is a result of ongoing work to support NASA’s New Horizons mission, scheduled to fly through the Pluto system in 2015. The mission is designed to provide new insights about worlds at the edge of our solar system. Hubble’s mapping of Pluto’s surface and discovery of its satellites have been invaluable to planning for New Horizons’ close encounter.
Hubble is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute in Baltimore conducts Hubble science operations and is operated for NASA by the Association of Universities for Research in Astronomy Inc. in Washington.