Key facts
- Mean diameter
- 2,376 km
- Mass
- 1.303 × 10^22 kg (0.00218 Earths)
- Surface gravity
- 0.62 m/s² (0.0632 g)
- Escape velocity
- 1.21 km/s
- Mean temperature
- -225 °C
- Rotation period
- 153.3 hours (retrograde)
- Orbital period
- 90,560 days
- Mean distance from the Sun
- 5,906.4 million km
- Sunlight travel time
- 5 h 28 min
- Axial tilt
- 122.5°
- Confirmed moons
- 5
Atmosphere
Thin nitrogen atmosphere with methane and carbon monoxide, layered with haze.
Composition and structure
Rock and ice; surface ices of nitrogen, methane and carbon monoxide.
Discovery and exploration
Discovered by Clyde Tombaugh in 1930. Reclassified as a dwarf planet by the IAU in 2006. New Horizons flew past on 14 July 2015.