Subscribe to our free daily newsletters
. 24/7 Space News .




Subscribe to our free daily newsletters



Astronomers Measure The Most Distant Moon

NASA file image of Pluto and Charon.

Paris (AFP) Jan 04, 2006
An international team of astronomers says the most distant moon in the Solar System, Charon, which orbits Pluto, is an icy rock that has no sign of an atmosphere.

They achieved the feat by observing Charon as it passed in front of a star last July -- an event that has been witnessed only once before in the past quarter-century.

Under this so-called occultation process, light from the star is dimmed and refracted as it passes through an object's atmosphere but is barely touched if the object has no atmosphere.

Using the high-powered European Southern Observatory (ESO) telescope located in the dry mountains of Chile's Atacama Desert, the astronomers determined that Charon has a density of about 1.71 of that of water.

That indicates the moon is an icy body, with rock comprising about half its volume.

The density is also very similar to that of Pluto's, and could back theories that the planet wacked into a large space object, causing a large chunk to break off and eventually be enslaved as a satellite.

The occultation also yielded a remarkably accurate measurement of Charon's size.

It has a diameter of between 1,206 and 1,212 kilometers (753.75 and 757.5 miles), give or take five kms (3.1 miles). It is almost half the size of Pluto's 2,300 kms (1,437 miles).

Pluto, discovered in 1930 by the American astronomer Clyde Tombaugh, is the outermost of the recognised planets, although a new contender for that title emerged last year in the form of an object called 2003 UB313.

Charon was discovered in 1978. It orbits so close to Pluto, at a distance of less than 20,000 kms (12,000 miles) that some astronomers have wondered whether they should be classified as a double planet system rather than mother and satellite.

The pair circle the Sun at a distance ranging from 4.5 to seven billion kms (2.81-4.37 billion miles), and take 248 Earth years to complete a single orbit.

A mission by the US space agency NASA to explore Pluto and Charon is scheduled for liftoff later this month, with a launch window opening on January 17. The 700-million-dollar unmanned probe, New Horizons, will take nine years to reach its goal.

The two studies, headed by Amanda Gulbis of the Massachusetts Institute of Technology (MIT) and Bruno Sicardy of the Paris Observatory, appear on Thursday in Nature, the British weekly science journal.

Source: Agence France-Presse

Related Links
SpaceDaily
Search SpaceDaily
Subscribe To SpaceDaily Express



Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News


New Horizons Launch Vehicle Fully Assembled For Voyage To Pluto
Cape Canaveral FL (SPX) Dec 27, 2005
This past week was a busy one for New Horizons. Mission operations practices continued, as did engineering paperwork closeouts.







  • Microbes Survive Firey Plunge By Columbia
  • Spicing Up Space Meals
  • SpaceDev Appoints New Chief Executive Officer And Vice Chairman
  • ZeroG Aerospace Launches Affordable Space Tourism for the Masses

  • Mission To Mars Via Antarctica
  • NASA's Spirit And Opportunity Still Probing Mars After Two Years
  • NASA Mars Rover Spirit Studying Algonquin
  • Evaluating Arm Positions Offer Many Opportunities On Marsby Staff Writers

  • ILS to Launch ASTRA 1KR in 2006
  • Telematic Solutions Awarded EUR8Mn Contract For Vega Pad Work In Kourou,
  • Telematic Solutions Awarded EUR8Mn Contract For Vega Pad Work In Kourou,
  • ILS Atlas V Gets Go Ahead To Launch Defense Weather Satellite

  • Indian Remote Sensing Sat Completes Ten Years
  • Sahara's Edge Studied From Ground, Air And Space To Improve Water Management
  • A New Generation Of Russian EO Satellites In Orbit
  • New Era Of Low Cost EOs Dawns As First Topsat Images Received

  • Astronomers Measure The Most Distant Moon
  • New Horizons Launch Vehicle Fully Assembled For Voyage To Pluto
  • The Ice Dwarf Cometh
  • NASA Sets Sights On First Pluto Mission

  • Galaxy's Neighboring Spiral Arm Is Closer Than Thought
  • Partial Ingredients For DNA And Protein Found Around Star
  • Pulsar Racing Through Space Reveals A Comet Like Trail
  • Astronomers Link Old Stars And Mysterious Cosmic Explosions

  • An Explosion On The Moon
  • SMART 1 Uses New Imaging Technique In Lunar Orbit
  • Moon Storms
  • Chinese Lunar Land Sale A Great Idea But Illegal Says Government

  • SiRFstarIII Featured in TomToms Innovative Portable Navigation Product
  • EGNOS Demonstration In South Africa
  • Europe Opens Up Civil Navigation System With Galileo Satellite
  • British Built Navigation Satellite Is First For Europe

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement