Neptune Facts

Neptune Facts

Want to know more about Neptune? Well keep reading for some interesting facts on this cool planet.

Neptune facts

Neptune is the eighth planet from the Sun. This makes it the planet that is the most distant in the solar system.

Neptune is a gas giant planet and it is thought that it may have formed much closer to the Sun in earlier solar system history, before it got to the position it is in today.

It is also the third largest planet in the solar system after Jupiter, Saturn and Uranus.

Neptune Overview

Mass: 225,775,402,703,533,120 billion pounds (102,410,000,000,000,000 billion kilograms)

Equatorial Diameter: 49,528 km

Polar Diameter: 30,249 miles (48,682 kilometers)

Equatorial Circumference: 96,685 miles (155,600 kilometers)

Known Moons: 14

Notable Moons: Triton

Known Rings: 5

Orbit Period: 60,190.03 Earth days (164.79 Earth years)

Surface Temperature: -201 °C

The History of Neptune

  • Neptune was discovered on 23 September 1846 by Urbain Le Verrier and Johann Galle in Berlin.
  • Apparently the existence of the planet had been discovered a year earlier in 1845.
  • Did you know that this planet was not known to the ancients, unlike most other planets? The reason for this is that you can’t see it with the naked eye, which is why it was discovered so late in comparison to the other planets.
  • Its position was discovered using mathematical predictions.
  • It was named after the Roman god of the sea.

Neptune god of the sea

Interesting Facts about Neptune 

How does Neptune spin on its axis?

Neptune actually spins on its axis very quickly. Its equatorial clouds take 18 hours to make one rotation. The reason for this is that Neptune is not a solid body of planet. 

What size is Neptune in relation to other planets?

Neptune is actually the smallest of the ‘ice giants’. Even though it is smaller than Uranus, Neptune has a greater mass.

What is Neptune’s atmosphere made up of?

Neptune’s atmosphere is made up of about 80% hydrogen and 19% helium. It also has a small amount water and methane. This gives it its green-bluish color.

The dark blue and bright white features of the atmosphere help to tell Neptune from Uranus apart from each other as they actually look quite similar. The thin cirrus-like white clouds contain methane ice. 

How far is Neptune from the Sun?

It’s pretty far that’s for sure. It is 310,685,596 miles (500,000,000) kilometers from the Sun.

Neptune distance from Sun

(Neptune’s distance from the Sun – click to enlarge)

What is Neptune’s climate like?

Well let’s just say that it’s very active up there in Neptune. Massive storms whirl through its upper atmosphere, and high-speed winds make their way around the planet at up 1,968 feet (600 meters) per second. That is fast!

One of the largest storms ever seen was recorded in 1989. It was called the Great Dark Spot. It lasted for about five years.

Does Neptune have rings?

It actually does have a very thin collection of rings. They are most likely to be made up of ice particles mixed with dust grains and maybe even coated with a carbon-based substance. 

Neptune's rings

How many moons does Neptune have?

  • Neptune has 14 moons in total. The most interesting moon is Triton, a frozen world that is churning out nitrogen ice and dust particles from below its surface. It was most likely captured by the gravitational pull of Neptune. It is also thought that it is probably the coldest world in the solar system.

Triton moon

  • Triton is a rather unusual moon when compared to others. This is because it orbits Neptune in the opposite direction of Neptune’s own rotation on its axis.  All the other major moons in the solar system follow their planets round as they turn.
  • Triton is about the same size as our own moon.  A smaller moon, Nereid, was discovered by telescope in 1949 and six further moons were discovered in the 1980s by the Voyager spacecraft.  All these moons are between Triton and Neptune.

When did Neptune complete its first Orbit of the Sun? 

In 2011 Neptune completed the first orbit of the Sun since its discovery 165 years before in 1846. 

How many space missions have flown by Neptune?

Well unbelievably there’s only been one. In 1989, the Voyager 2 spacecraft swept past the planet. It returned the first close-up images of the Neptune system.

Voyager 2 Neptune

The NASA/ESA Hubble Space Telescope has also studied this planet, as have a number of telescopes that are on the ground.

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