Planet
Neptune
The planet found by math, on a 165-year orbit.
Neptune takes almost 165 Earth years to circle the Sun, so it completed its first full orbit since its 1846 discovery only in 2011. Its 28-degree tilt gives it seasons that each last more than 40 years. Pluto crosses inside Neptune's orbit, yet a 3:2 orbital rhythm keeps the two from ever meeting.
How it moves
- Neptune orbits the Sun every 60,189 days (164.8 Earth years) at an average of 5.45 km/s.
- It rotates once every 16.11 hours.
- A 28.32-degree axial tilt gives Neptune seasons, each lasting more than 40 years.
- For every three laps Neptune makes around the Sun, Pluto makes two, a resonance that prevents close approaches.
- Its position was predicted from unexplained tugs on Uranus's orbit before anyone saw it.
Facts
- Mean radius
- 24,622 km
- Mass
- 1.024e+26 kg
- Surface gravity
- 11.27 m/s²
- Rotation period
- 16.11 hours
- Orbital period
- 60,189.018 days
- Average distance from the Sun
- 30.06896348 AU
- Eccentricity
- 0.0097
- Axial tilt
- 28.32°
- Mean orbital speed
- 5.45 km/s
- Known moons
- 16
- Discovered
- September 23, 1846, by Johann Gottfried Galle, at the position predicted by Urbain Le Verrier
Neptune finished its first full orbit since its discovery in 2011, 165 years after being found.
Sources: nssdc.gsfc.nasa.gov, science.nasa.gov, science.nasa.gov