Neptune's moon, Triton, is slowly getting closer to Neptune. Eventually, it will get so close that it may get torn apart by Neptune's gravity and possibly form rings more spectacular than Saturn's.
The strongest winds in the Solar System have been recorded on Neptune, at speeds of up to 2,000 kilometres per hour.
Neptune has dark spots similar to the Great Red Spot on Jupiter. These are areas of high atmospheric pressure which force clouds of methane gas high up into the atmosphere, appearing like cirrus (thin, whispy) clouds on Earth. However, these spots disappear and reappear on different parts of the planet, unlike Jupiter's spot.
Neptune sometimes orbits the Sun further away than Pluto. From 1979 to 1999, Pluto was closer to the Sun than Neptune. As Pluto was classified as a planet at the time, Neptune was then the ninth planet from the Sun.
Triton orbits Neptune in the opposite direction to the planet's rotation. It is the only large moon in the Solar System to do this.
Neptune has four faint rings. Some parts of these rings are brighter in areas than others and appear like arcs orbiting the planet. Maybe they are still forming.
Since its discovery in 1846, Neptune has completed only one full orbit of the Sun. In fact, it takes 165 years for the planet to go around the Sun.
Neptune was discovered when scientists noticed something peculiar about Uranus' orbit, believing something to be pulling it in the opposite direction to the Sun's pull of gravity. They calculated the position of a planet and soon afterwards, discovered Neptune.
The coldest temperatures measured in the Solar System (-230°c) have been recorded on Neptune's moon, Triton.
Pluto, a dwarf planet which has an orbit which sometimes crosses Neptune's, may have been a moon of Neptune which escaped the planet's pull of gravity, but being prevented from escaping the Solar System by the gravitational pull of the Sun.
| Name | Neptune |
| Meaning of Name | Roman god of the Sea (Greek equivalent is Poseidon) |
| Name in Foreign Languages | Neptune (French), Neptuno (Spanish, Portuguese), Neptun (German, Russian), Nettuno (Italian), Neptunus (Latin), Poseidon (Greek) |
| Average Distance from the Sun |
4,498,252,900 km / 2,795,084,800 miles / 30.069 A.U. Comparison with Earth: 149,597,890 km / 92,955,820 miles / 1.000 A.U. |
| Closest Distance to the Sun (Perihelion) |
4,459,630,000 km / 2,771,087,000 miles / 29.811 A.U. Comparison with Earth: 147,100,000 km / 91,400,000 miles / 0.983 A.U. |
| Farthest Distance from the Sun (Aphelion) |
4,536,870,000 km / 2,819,080,000 miles / 30.327 A.U. Comparison with Earth: 152,100,000 km / 94,500,000 miles / 1.017 A.U. |
| Diameter across equator | 49,528 km / 30,776 miles Comparison with Earth: 12,756 km / 7,926 miles |
| Diagram showing planet's size compared to the size of Earth |
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| Circumference around equator |
155,597 km / 96,683 miles Comparison with Earth: 40,074 km / 24,901 miles |
| Mass | 102,440,000,000,000,000,000,000,000 kg Comparison with Earth: 5,973,700,000,000,000,000,000,000 kg |
| Time to spin on Axis | 16 hours, 6.5 minutes Comparison with Earth: 23 hours, 56 minutes |
| Time to orbit the Sun | 164.79 Earth years or 60,190 days Comparison with Earth: 365 days, 6 hours |
| Distance planet travels to complete one orbit | 28,142,000,000 km / 17,487,000,000 miles Comparison with Earth: 924,375,700 km / 574,380,400 miles |
| Gravity (Earth = 1) | 1.1 |
| Escape Velocity | 85,356 km/h / 53,038 mph Comparison with Earth: 40,248 km/h / 25,009 mph |
| Temperature at Cloud Tops | -216 °c / -357 °F / 57 K Comparison with Earth's average temp: 15 °c / 59 °F / 288 K |
| Contents of Atmosphere | Hydrogen, Helium, Methane |
| Known moons | There are at least 13 moons known to orbit Neptune - Naiad, Thalassa, Despina, Galatea, Larissa, Proteus, Triton, Nereid, Halimede, Sao, Laomedeia, Psamathe, Neso |
| Past Missions (including nationality and year of launch) | Voyager 2 |
| Present Missions | Voyager 2 (USA, 1977. Reached Neptune in 1989) |
| Proposed or planned Missions | There are no proposed missions to Uranus |
