SAD LOVE QUOTES: Hubble telescope discovers that Pluto has a tiny fourth moon

Wednesday, July 20, 2011

Hubble telescope discovers that Pluto has a tiny fourth moon

Last updated at 7:49 PM on 20th July 2011

NASA has announced that the Hubble Space Telescope has found a fourth moon circling the icy dwarf planet, Pluto, but it is just eight to 21 miles wide.

Until astronomers decide upon a name, this moon will be called P4.

Astronomers had been looking to see if Pluto had a ring, but instead they found the tiny object circling the dwarf planet that is 3 billion miles from Earth.

Lost in space: Pluto's moons including the newly discovered P4 are shown in this graphic from NASA

P4 is the smallest of Pluto's four moons, the U.S. space agency said in a statement.

Pluto's largest moon, Charon, is 750 miles across, while its other moons, Nix and Hydra, are 56 and 70 miles in diameter respectively. Pluto itself is 1442 miles wide.

For comparison, Earth's moon is 2158 miles wide.

The space telescope was searching for rings around the planetary oddball at the edge of our solar system when it came across P4.

Mark Showalter of the SETI Institute in Mountain View, California, who led this observing program with Hubble said: '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.'

The observation by Hubble is part of ongoing work to support NASA's New Horizons mission, scheduled to have a close encounter with Pluto and its moons in 2015.

Hubble's mapping of Pluto's surface and discovery of its satellites have been invaluable to planning for New Horizons' close encounter.

Moon with a view: An artist's impression of the Pluto system from the surface of one of the outer moons. Pluto is the large disk at centre, while Charon, the largest moon, is to the right of Pluto

'This is a fantastic discovery,' said New Horizons' principal investigator Alan Stern of the Southwest Research Institute in Boulder, Colo. 'Now that we know there's another moon in the Pluto system, we can plan close-up observations of it during our flyby.

'Pluto's satellite system is truly knocking our socks off with surprises — it's magnificently complex, and getting more crowded all the time. I can't wait till we get there to see what other surprises this planet and its moons have in store for us!

P4 is located between the orbits of Nix and Hydra, both of which were discovered by Hubble in 2005. Charon was discovered in 1978 by the U.S. Naval Observatory.

Pluto itself was only discovered in 1930, and from its discovery until 2006 was classified as a planet.

All four of Pluto's moons are believed to have formed when Pluto and another planet-sized body collided in the early history of our solar system. Earth's Moon may have formed the same way.

P4 was first seen in a photo taken by Hubble on June 28 and was confirmed in subsequent Hubble pictures taken July 3 and July 18, NASA said.

Lunar rocks returned to Earth from the Apollo missions led to the theory that our moon was the result of a similar collision between Earth and a Mars-sized body 4.4 billion years ago.

Scientists believe material blasted off Pluto's moons by micrometeoroid impacts may form rings around the dwarf planet, but the Hubble photographs have not detected any so far.

'This surprising observation is a powerful reminder of Hubble's ability as a general purpose astronomical observatory to make astounding, unintended discoveries,' said Jon Morse, astrophysics division director at NASA Headquarters in Washington.

New Horizons will fly by Pluto in July 2015. Its instruments will carry out detailed mapping of the object's surface features, composition and atmosphere.

The probe will go to about 10,000km from Pluto and about 27,000km from Charon, before pressing onwards to other objects in the Kuiper Belt, a region of space that contains many frozen leftovers from the birth of our Solar System.