planet
Neptune
Found in 1846 by pointing a telescope exactly where Le Verrier said the arithmetic required a planet to be. Winds there run supersonic at 2,100 km/h, the fastest anywhere in the system.
Position
Computed on . For a continuously updating figure, open the live simulation.
When to look
Neptune 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 | 28.88 AU | |
| opposition | 28.87 AU | |
| opposition | 28.86 AU | |
| opposition | 28.86 AU |
About Neptune
Neptune was found by mathematics before it was found by telescope: discrepancies in Uranus’s motion led Le Verrier to predict a position, and Galle found the planet within a degree of it on the first night of looking, in 1846. It has completed only one orbit since. Winds reach 2,100 km/h, the fastest measured anywhere in the solar system, on a world receiving barely a thousandth of Earth’s sunlight.
Physical data
- Diameter
- 49,528 km
- Mass
- 17.1 earths
- Surface gravity
- 11.15 m/s2
- Rotation
- 16h 06m
- Year
- 164.8 y
- Axial tilt
- 28.3 deg
- Cloud tops
- -201 C
- Moons
- 16
Positions from VSOP87, accurate to within one arcminute. Physical constants are published values and are not computed here.