Moons of Pluto while searching for Plutonian rings. Styx, announced on 7 July 2012, was discovered while looking for potential hazards for "New Horizons". Charon is about half the diameter of Pluto and is so massive (nearly one eighth of the mass of Pluto) that the system's barycenter lies between them, approximately 960 km above Pluto's surface. Charon and Pluto are also tidally locked, so that they always present the same face toward each other. The IAU General Assembly in August 2006 considered a proposal that Pluto and Charon be reclassified as a double planet, but the proposal was abandoned. Pluto's four small
Atmosphere of Pluto it was possible to calculate its distance from Pluto's center. Subtracting the modern figure for the radius of Pluto, the result is a height of ; hence this "haze" is indistinguishable from the surface of Pluto. During later occultations (when the atmosphere of Pluto was already denser) this kink was absent. Another evidence of the haze was obtained in 2002 due to a new occultation. The stellar light which managed to reach Earth during the occultation (due to refraction in Pluto's atmosphere), demonstrated an increase of intensity with wavelength. This was interpreted as a reliable evidence of light scattering by