dwarf planet
Pluto
Reclassified as a dwarf planet in 2006. For twenty years of every circuit it runs inside the orbit of Neptune, but a 3:2 resonance guarantees the two can never meet.
Position
Computed on . For a continuously updating figure, open the live simulation.
When to look
Pluto is best placed at opposition, when Earth passes between it and the Sun. It then rises at sunset, stands highest at midnight, and is at its closest and brightest.
| Date (UTC) | Event | Distance from Earth |
|---|---|---|
| opposition | 34.81 AU | |
| opposition | 35.07 AU | |
| opposition | 35.33 AU | |
| opposition | 35.59 AU |
About Pluto
Pluto’s orbit is both eccentric and steeply inclined, carrying it inside Neptune’s orbit for twenty years of every 248-year circuit — most recently from 1979 to 1999. The two can never collide: a 3:2 mean-motion resonance means Pluto completes two orbits for every three of Neptune’s, and the geometry keeps them permanently apart. Charon is large enough relative to Pluto that the two orbit a barycentre outside Pluto’s surface.
Physical data
- Diameter
- 2,377 km
- Mass
- 0.0022 earths
- Surface gravity
- 0.62 m/s2
- Rotation
- 6.39 d
- Year
- 247.9 y
- Axial tilt
- 122.5 deg
- Mean temperature
- -229 C
- Moons
- 5
Positions from VSOP87, accurate to within one arcminute. Physical constants are published values and are not computed here.