NEW HORIZONS • Low surface gravity, about 6% of Earth’s. • Estimated surface temperature is about minus-233 degrees Celsius (minus-387 degrees Fahrenheit) with strong variations across the surface. • Has a density about twice that of water, indicating it is composed of a mixture of ice and rocky material. • With ranges of very bright and dark areas, Pluto’s surface has more contrast than any other planet in the outer solar system. Physical Characteristics: Charon • Diameter is about 1,200 kilometers (745 miles), the largest satellite relative to the planet it orbits. • Surface known to be mostly water ice, possibly also including ammoniated hydrates. • No detectable atmosphere (from Earth-based studies). • Like Pluto, its density (about twice that of water) indicates it is composed of a mixture of ice and rocky material. For more information, visit: http://www.pluto.jhuapl.edu/science/scienceOver.html NASA’s First Mission to Pluto and the Kuiper Belt 7