Fact: General facts about Neptune


Neptune is the 8th planet out from the sun and the last of the gas giants. It was discovered 1846 after astronomers noticed that Uranus was moving in a way that suggested another planet’s gravity was tugging on it. It is a cold blue planet was some of the fastest winds ever recorded.

Facts About Neptune

Name Origin: Roman. Although not discovered by the ancient sky watchers, because it is so faint in the sky, after it was discovered there was a short debate about what the planet should be called. Eventually it was decided to use Neptune who was the Roman god of the sea, and the equivalent of the Greek Poseidon

Size: Average Diameter 50,000km, Mass of approximately 1.02 x 10^26 kg. Neptune is a bit more than 3.8 times as wide as Earth, and could fit more than 57 Earths inside of it! Even though this is quite large, it still makes Neptune the smallest of the gas giants.

Gravity: 1.14g. Even though Neptune is larger than Earth, it has a low density and not much more gravity. If you weight 150lbs on earth you would only weigh 171lbs on Uranus!

Temperature: The surface temperature of Uranus averages a very chilly -200 degrees C!

Days: Rotational period 16 hours. Neptune spins more quickly than Earth even with its much larger size. There are almost 2 days on Neptune for every one day on Earth!

Orbit: Semi Major Axis: 4.5 Billion km, Orbital Period 60,000 days. Neptune is more than 30 times as far away from the Sun as the Earth is, and a single year on Uranus takes more than more than 164 years on Earth. It has only made one trip around the sun since it was discovered in the 19th century!

Atmosphere: Hydrogen, Helium. Deeper below the atmosphere, Neptune is mostly made of fluid “icy” materials including water, methane, and ammonia.

Visible Features: Due to very fast winds, Neptune had several large storms that were visible when the Voyager probe visited it in 1989. One was called the Great Dark Spot, and another was white and called Scooter!

Fun facts: Because they are very similar in size, color, composition, and position in the solar system, Neptune and Uranus are often called the ‘sister planets’. As of 2015 the only space probe that has had the chance to visit them was the Voyager 2 probe which took more than 10 years to reach Neptune!

To learn more about Neptune visit:

  • Neptune: The Windiest Planet


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