pluto 2

Matthew Berkowitz Science PLUTO 11-9-99 Pluto is the farthest planet from the Sun (usually) and by far the smallest. Pluto is smaller than seven of the solar systems moons (the Moon, Io, Europa, Ganymede, Callisto, Titan and Triton). Orbit: 5,913,520,000 km (39.5 AU) from the Sun (average) Diameter: 2274 km Mass: 1.27e22 kg In Roman mythology, Pluto (Greek: Hades) is the god of the underworld. The planet received this name (after many other suggestions) perhaps because it's …

…and methane. It is extremely tenuous the surface pressure being only a few microbars. Pluto's atmosphere may exist as a gas only when Pluto is near its perihelion; for the majority of Pluto's long year, the atmospheric gases are frozen into ice. Near perihelion, it is likely that some of the atmosphere escapes to space perhaps even interacting with Charon. The Pluto Express mission planners want to arrive at Pluto while the atmosphere is unfrozen.