Last updated on April 18, 2014 at 7:09 EDT
Compass and Scale Image of Pluto
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Compass and Scale Image of Pluto

July 30, 2012
This image, taken by NASA's Hubble Space Telescope, shows five moons orbiting the distant, icy dwarf planet Pluto. The newly discovered small moon, designated P5, is the innermost of the moons found by Hubble over the past seven years. The diagram shows that P5 is in a 58,000-mile-diameter circular orbit around Pluto that is assumed to be co-planar with the other satellites in the system. Though Charon (discovered in 1978) is an even closer moon to Pluto, some astronomers consider the Pluto-Charon pair a "double planet" because of Charon's is 12 percent of Pluto's mass (by comparison our Moon is .01 percent Earth's mass). This image was taken with Hubble's Wide Field Camera 3 on July 7. Other observations that collectively show the moon's orbital motion were taken on June 26, 27, and 29, 2012 and July 9, 2012. The new data will help scientists in their planning for the July 2015 flyby of Pluto by NASA's New Horizons spacecraft. Illustration Credit: NASA, ESA, and L. Frattare (STScI) Science Credit: NASA, ESA, and M. Showalter (SETI Institute)