Neptune is the Roman god of fresh water and the ocean. His counterpart in Greek mythology is the god Poseidon. Neptune was the brother of Jupiter and Pluto.
How much would you weigh on Neptune?
If you weigh 70 pounds (32 kg) on the Earth, you would weigh 78.5 pounds (36 kg) on Neptune. Neptune’s gravitation factor relative to Earth is 1.19.
For many, centuries people did not know that this planet even existed. Neptune was discovered in 1846. Here is where it gets a little tricky. Johann Gottfried Galle, using Urbain Le Verrier and John Couch Adams calculations, found Neptune. What this means is that Neptune’s discovery is a joint British-French-German discovery. Neptune is the smallest of the four gas giants in our Solar System. Much like Saturn and Uranus, Neptune’s atmosphere contains hydrogen, helium, and methane. Because of the methane in Neptune’s outer atmosphere, all the red light from the Sun gets absorbed but the blue light gets reflected back. Thus, Neptune appears blue.
Neptune’s anniversary portrait from the Hubble Telescope. Neptune’s atmosphere is what makes it blue!
We didn’t know much about Neptune until the spacecraft Voyager 2’s expedition on August 25, 1989. Voyager 2 took many pictures of the planet. Much of what we know today about Neptune came from this single visit. We saw a brilliant blue planet with a few thin white clouds laced around its surface.
Clouds and Storms
In Neptune’s atmosphere, there is a large white cloud that moves around rather quickly. The “scooting” of this cloud around the atmosphere is why it’s named “Scooter.”
When Voyager 2 visited Neptune, its pictures showed a giant storm much like the storm on Jupiter. This storm isn’t the “Great Red Spot”, it’s the “Great Dark Spot”. It appears as a dark oval shape on the surface of the planet. We do not know how long this storm has been active or if it is still present.
More recently, the Hubble Space Telescope sent pictures and there was no sign of the Great Dark Spot. These pictures did show two other dark spots that eventually faded away.
Changes in the Great Dark Spot over time.
Neptune is a very windy place. No other planet in the Solar System has winds that are as strong as Neptune’s. The winds near the Great Dark Spot could have reached nearly 1,200 miles per hour (approx 1931 km per hour). Perhaps this windy atmosphere contributes to the appearance and disappearance of the great dark spots.
An Odd Orbit
Neptune’s circular orbit is offset from the Sun. At times, Neptune’s orbit takes it further from the Sun than any other planet in the Solar System. In 2011, Neptune completed its first orbit around the Sun since it was discovered in 1846.
Neptune has six rings which circle the planet. Scientists believe these rings are fairly new. The rings are more irregular than the rings of other planets. There are areas of varying thickness throughout the rings.
Neptune has 14 moons that we know of. Because Neptune is so far away, it is difficult to see any of these moons. There are probably many more moons orbiting this blue planet. We just haven’t seen them yet.
The first moon discovered was Triton. An amateur astronomer in England named William Lassell discovered it. He found it only 17 days after Galle discovered Neptune in 1846.
The other moons are: Despina, Galatea, Halimede, Laomedeia, Larissa, Naiad, Nereid, Neso, Proteus, Psamathe, Sao, and Thalassa. Discovered July 1, 2013, the current name of the newest moon of Neptune is S/2004 N 1.
Neptune’s moons are very hard to find.