Pluto

Pluto &Charon

Discovered in 1930, Pluto appears to be little more than a celestial snowball. Ground-based observations indicate that Pluto's surface is covered with methane ice and that there is a thin atmosphere that may freeze and fall to the surface as the planet moves away from the Sun. Observations also show that Pluto's spin axis is tipped by 122 degrees.

The planet has one known satellite, Charon, discovered in 1978. Charon's surface composition is different from Pluto's: the moon appears to be covered with water-ice rather than methane ice. Its orbit is gravitationally locked with Pluto, so both bodies always keep the same hemisphere facing each other. Pluto's and Charon's rotational period and Charon's period of revolution are all 6.4 Earth days.

The image above is a Hubble Space Telescope (HST) image of Pluto and its satellite Charon. Pluto is 2320 km in diameter and Charon is 1270 km. The two bodies are so close in size they are often thought of as a double planet. At the time this image was taken the two bodies were at maximum elongation of 0.9 arc seconds. The bodies orbit 19,640 km apart. Pluto is the larger body to the lower left, Charon is at upper right.

Planetary Data of Pluto

Rotation Period (Equatorial)

6.39 days

Average distance from sun

4293 700 000 to 7533 300 000 Km

Sidereal Orbit Period

90465 days

Sidereal Rotation Period

153 hours

Average Orbital Velocity

4.75 km/sec

Radius of Planet (Polar)

? km

Radius of Planet (Equatorial)

2320 km

Mass of Planet

1.25 x 10²² kg

Density of Planet

2050 kg/m³

Temperature (Upper atmosphere)

-370 ºF

 

 

Atmosphere

Methane, Nitrogen

Satellites

Charon