Recent images taken by the Hubble Space Telescope show that Pluto?s three moons are the same color, lending support to the theory that they were formed by a single, giant collision 4.6 billion years ago.
The discovery was made by a research team headed by Hal Weaver of the Johns Hopkins University Applied Physics Laboratory and Alan Stern of the Southwest Research Institute.
Charon, Pluto?s largest moon, was discovered in 1978.
The planet?s smaller two other moons, S/2005 P1 and S/2005 P2, were found in 2005. The Hubble images show that the three moons share the same color and reflect sunlight with equal efficiency at all wavelengths.
“The high quality of the new data leaves little doubt that the hemispheres of P1 and P2 that we observed have essentially identical, neutral colors,” Weaver said.
“Everything now makes even more sense,” Stern added. “If all three satellites presumably formed from the same material lofted into orbit around Pluto from a giant impact, you might well expect the surfaces of all three satellites to have similar colors.”
The observations are part of an ongoing study of Pluto and its satellites that will culminate in July 2015 when NASA?s New Horizons mission, which was launched on Jan. 19, is scheduled to fly through Pluto?s system.
Other members of the Hubble Space Telescope Pluto observing team include Max Mutchler of the Space Telescope Science Institute in Baltimore, and Marc Bule of Lowell Observatory in Flagstaff, Ariz.
Finding Pluto: A brief history
The astronomer Clyde Tombaugh discovered Pluto at Lowell Observatory in Arizona 1930. Speculation about its existence, due to its effect on the orbit of Neptune, had been around for at least 15 years.
There is some debate about whether it is a planet or one of several thousand trans-Neptunian celestial bodies of comparable size, though most astronomers still refer to it as a planet.
Its cold atmosphere is composed of nitrogen, methane and carbon monoxide. Because it is the only one that has not been visited by a spacecraft, it remains the least known of our solar system?s planets. – Stephen Goode
