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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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Three's Company for Pluto
1 November 2005 (All day)
Astronomers have discovered two new moons around Pluto, raising the planet's known number of satellites to three. Measuring some 50 to 150 kilometers across, the new moons are much smaller than Charon, the 1192-km diameter satellite of Pluto discovered in 1978. Astronomers believe the small moons, temporarily designated S/2005 P1 and S/2005 P2, may be rubble from the same primordial collision that gave birth to Charon and could shed new light on the early history of the outer solar system.
The new moons were first spotted on 15 June by Max Mutchler, an instrument analyst at the Space Telescope Science Institute in Baltimore, Maryland. He was studying photos of Pluto taken on 15 and 18 May by the Hubble Space Telescope as part of a dedicated satellite search. Last week, astronomers Marc Buie of Lowell Observatory in Flagstaff, Arizona, and Eliot Young of the Southwest Research Institute (SwRI) in Boulder, Colorado, also found the two tiny moons on Hubble photos made on 14 June 2002. The discovery was subsequently announced on Halloween in an electronic circular by the International Astronomical Union. "I thought it was a Trick-or-Treat joke for a moment," says Jim Christy, the discoverer of Charon.
Alan Stern of SwRI, a member of the discovery team headed by Hal Weaver of Johns Hopkins University in Baltimore, says he is surprised by how compact Pluto's satellite system is. Charon orbits Pluto at a distance of some 22,000 kilometers, while the new moons are about 50,000 and 65,000 kilometers away. Christy says he thought additional satellites this close to the planet would be unlikely, given the disruptive gravitational tug of Pluto and Charon.
Attempts in September to see the new satellites with large ground-based telescopes were unsuccessful, and final confirmation of their existence will have to await new Hubble observations in mid-February 2006. By then, NASA will have launched its New Horizons spacecraft, set to flyby Pluto in the summer of 2015 (ScienceNOW, 11 August 2004:). "We [now] have four objects to divide our attention among at Pluto, rather than two," says Stern, who is New Horizon's principal investigator. "I wish we had a second spacecraft, given the richness of the system."