Hubble spies two maybe-moons orbiting Pluto

Confirmation to follow in February

Astronomers using the Hubble Space Telescope think they may have identified two previously unknown moons orbiting Pluto.

Any discovery to do with Pluto is particularly useful because despite its much debated planet-status, it is a Kuiper Belt object, meaning it is a remnant of the very earliest era of the solar system. The Kuiper Belt is an icy region beyond Neptune, and is also thought to be the place most comets come from.

Pluto with Charon and two candidate moons. Image: NASA

The candidate moons are around 5,000 times fainter than Pluto, and appear to orbit the planet at a distance of around 27,000 miles, two to three times as far away as Pluto's confirmed moon Charon. The possible satellites were first imaged on 15 May 2005 with follow up images taken three days later.

If the discovery of the moons is confirmed, scientists say it will further understanding of how the Pluto system evolved, as well as shedding new light on other Kuiper Belt objects with satellites, and the Kuiper Belt region in general.

"If, as our new Hubble images indicate, Pluto has not one, but two or three moons, it will become the first body in the Kuiper Belt known to have more than one satellite," said Hal Weaver of the Johns Hopkins Applied Physics Laboratory, co-leader of the team that made the discovery.

The researchers are planning to make follow up observations in February next year, which should provide the confirmation needed for the candidate moons to be allocated names. ®

Bootnote: There has been no official mention of the possibility that the two so-called "new moons" are in fact the earliest arrivals of a Dalek invasion fleet. However, no one has denied it either.