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Neptune

Subject:

Science  

Grades:

5, 6  

Mercury  Venus  Earth  Mars  Jupiter  Saturn  Uranus  Neptune  Pluto

Neptune

Classified by size, Neptune is one of the giant planets. These are also known as the gas giants. The other three gas giants are Jupiter, Uranus and Saturn. These gas giants all have diameters greater than 48000 kilometers.

The other five planets are called the small planets. The small planets all have diameters less than 13000 kilometers.

Where is It?
Neptune is the eighth, or second last, planet in our solar system. It is located between Uranus and Pluto, and is a very long way away from the Sun. Its average distance from the Sun is almost 4.5 billion kilometers., or over thirty times the distance from Earth to the Sun. The orbit, or path, Neptune follows around the Sun is almost a perfect circle. The closest Neptune gets to the Sun is about 4.3 billion kilometers., and the furthest away it gets is a little over 4.6 billion kilometers. At this distance, the Sun is just another bright light in Neptune’s sky.

How Did It Get Its Name?
Neptune is named after the Roman god of the sea.

How long are its years and days?
Since Neptune is so far away from the Sun, a year on Neptune lasts for 165 Earth years. Although a day on Neptune is shorter than a day on Earth. This gas planet spins, or rotates, once every sixteen hours.

How Big Is It?
Neptune is about 49500 kilometers. in diameter, about four times the size of Earth, which is about 12800 kilometers. in diameter. Neptune and Uranus are almost the same size, but both seem tiny in comparison to mighty Jupiter, which is almost three times as large as either of them.

Can It Be Seen From Earth?
Neptune can be seen with binoculars, but a telescope gives a much better view. Neptune is no larger than Uranus but is much further away, so it is harder to see.

What Is It Made Of?
Neptune has a small central core, or ball, made of up melted rock. Above the rocky center, the planet is covered by extremely cold water, which eventually changes into the top layer of hydrogen and helium, with a little methane mixed in. The methane gives Neptune its color.

What Is It Like on The Surface?
Since Neptune is a gas planet, it does not have a solid surface. In spite of this, Neptune has some of the most unusual “weather” in the solar system. The winds on Neptune can blow as fast as 2000 kilometers. per hour at the planet’s equator.

How Many Moons Does It Have?
Neptune has eight moons that we know about and there may be more. There are only two that can be seen from Earth. One of them is Triton. The family of moons surrounding Neptune is unusual because Triton, the largest, is over 2600 kilometers. in diameter and the rest of them are tiny, some as small as 32 kilometers. in diameter.

Almost all of Neptune’s eight moons are too small to see from Earth, so what is known about them came from the Voyager space mission. Triton was the last solid object Voyager saw before it left the solar system. The spacecraft sent back pictures of nitrogen “geysers” erupting on Triton’s surface.

Does It Have Rings?
All the gas giants in our solar system, including Neptune have rings. The rings of Neptune are made up of fairly small, very dark clumps of rock. Scientists believe that most of these clumps are about the size of a small car. There is also a large amount of dust in the rings. One of the rings has a twist in it.

Who discovered it?
Some sources that the astronomers Galle and d’Arrest discovered Neptune on September 23, 1846, although other sources say that it was Adams in 1846.

Does it have any special features?
An interesting fact about Neptune is that astronomers were looking for it before it was know to exist. After William Herschel discovered Uranus, astronomers noticed that Uranus’ orbit didn’t seem to obey the laws of physics. Something was making Uranus move in unexpected ways. Astronomers decided that there must be another planet making Uranus move and they then calculated where the new planet might be.

Resources Used
Astronomy for Kids www.dustbunny.com/afk/
Small Worlds David Drew: Nelson, 1989
The Gas Giants David Drew: Nelson, 1989

Solar System Unit  |  Classification  |  Glossary

Images from: Astronomy Picture of the Day

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