Another small moon for Pluto…

By AAP with AG Staff 13 July 2012
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Pluto may have been dumped from the planet club, but astronomers have just discovered it’s one up on moons.

ASTRONOMERS ANNOUNCED ON Wednesday that they have found Pluto’s smallest moon yet, bringing the count of its known moons to five.

It’s an entourage greater than Mercury and Venus (neither of which have moons), and Earth and Mars combined.

“We’re not finished searching yet,” says Hal Weaver of Johns Hopkins University in Maryland, who thinks there may be more.

The discovery was made by a team of scientists who used the Hubble Space Telescope to scout out Pluto’s neighbourhood ahead of the arrival of NASA spacecraft, New Horizons, scheduled to fly by Pluto in 2015.

Pluto not dwarfed by its new mini moon

When the New Horizons craft launched in 2006, Pluto was a full-fledged planet, but amid controversy it has since been demoted to dwarf planet status by the International Astronomical Union.

The newfound moon – known as P5 until it gets a proper name – appeared as a faint fleck in the Hubble images.

Scientists estimated the mini-moon to be nine to 24km across, smaller than the still nameless one that they spotted last year, which is 12 to 33km wide.

Pluto’s largest moon, the 1000km-wide Charon, was discovered in 1978. Two smaller moons, Nix and Hydra, were found in 2005.

How Pluto got its moons.

The moons are thought to have formed after an ancient collision between Pluto and an object in the Kuiper Belt, a disk teeming with small bodies that lies beyond the orbit of Neptune.

Since the launch of the New Horizons mission, scientists have been studying the Kuiper Belt in search of debris that might pose a danger to the spacecraft.

Mark Showalter of the SETI Institute said names for the new moon and last year’s discovery would not be proposed until the team finishes analysing the Hubble data in case there were more hidden moons.