Its flight will take eight years, its estimated arrival date at the Pluto-Charon system is July 14, 2015.

The astronomers said this supported the hypothesis that the Pluto-Charon system formed out of the shattered remains of a collision sometime early in the solar system's history.

The Pluto-Charon system is unusual in that the center of mass lies in open space between the two, a characteristic sometimes associated with a double-planet system.

Some authors consider the Pluto-Charon system to be a double (dwarf) planet.

An extreme example of this is the Pluto-Charon system, where both bodies are tidally locked to each other.

A small crew of scientists had a research station on Charon, the outsized satellite that made the Pluto-Charon system into a small planetary doublet.

The center of mass (barycenter) of the Pluto-Charon system lies outside either body.

Such a situation already exists in the Pluto-Charon system.

Although most of the molecules then escape into space, the astronomers said, some form a gaseous cloud of methane surrounding the entire Pluto-Charon system.

Their combined mass is 1/6000th that of the Pluto-Charon system.