• Forum
• SITREP
• Military
• WMD
• Intelligence
• Homeland Security

• Space

• Introduction
• Systems
• Facilities
• Agencies
• Countries
• Hot Documents
• News
• Reports
• Policy
• Budget
• Congress
• Links

• Public Eye

Hubble Space Telescope Confirms New Pluto Moons

22 February 2006

Moons may have been born in collision of worlds 4 billion years ago

By Cheryl Pellerin
Washington File Staff Writer

Washington -- Follow-up observations with NASA's Hubble Space Telescope have confirmed the presence of two new moons orbiting the distant planet Pluto, according to a February 22 press release from the Space Telescope Institute in Maryland.

Hubble first discovered the moons in May 2005, but the science team probed more deeply into the Pluto system last week to look for more satellites and to characterize the moons’ orbits.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute conducts Hubble science operations for NASA.

The team did not doubt the moons were real but they expressed satisfaction that the moons showed up very close to the locations predicted from the earlier Hubble observations.

The initial discovery was reported in the February 22 edition of the British science journal Nature.

The confirmation reinforces the emerging view that the Kuiper Belt -- a swarm of icy bodies encircling the solar system beyond Neptune -- might be more complex and dynamic than astronomers once thought.

Pluto, discovered in 1930, resides inside the Kuiper Belt and is about 4.8 billion kilometers from the sun.

The moons' orbits are in the same plane as the orbit of the much larger satellite Charon, discovered in 1978.

This likely means the moons were not captured but were born, along with Charon, in what is theorized to have been a titanic collision between two Pluto-sized objects more than 4 billion years ago.

A team of astronomers, led by Hal Weaver of the Johns Hopkins University Applied Physics Laboratory in Maryland and Alan Stern of the Southwest Research Institute in Colorado, made the new observations February 15 with Hubble's Advanced Camera for Surveys.

The moons, called S/2005 P 1 and S/2005 P 2, are about 64,373 kilometers and 48,280 kilometers away from Pluto, respectively.

Astronomers believe the formation of the Pluto system is similar to that of the Earth and moon. In both cases a comparable-sized body slammed into the parent planet.

Simulations show that debris from the collision would go into an orbit around the planet and coalesce to form one or more satellites.

Investigating how Pluto ended up with three moons while the Earth has only one should yield valuable insights into the processes by which satellite systems form around planets.

The team will use Hubble again March 2 to study the new moons.

Images and more information are available on the HubbleSite Web site.

(The Washington File is a product of the Bureau of International Information Programs, U.S. Department of State. Web site: http://usinfo.state.gov)