Planet Neptune Facts: Lesson for Kids

Instructor: Lisa Hanson

Lisa is a Continuous Improvement Coach for her school district and has taught in elementary school for many years. She has a master's degree in curriculum and instruction.

For centuries, astronomers have been gazing up at the sky trying to discover what is beyond Earth. One planet in our solar system, Neptune, is very far away. Read this lesson to learn more about this distant planet.

Neptune, The Blue Planet

Looking up at the night sky we often see lots of twinkling stars, but some of those small lights in the sky are actually planets. Some planets are so far away we would need a telescope to be able to see them.

Neptune is too far away to see with just your eyes, but you can sometimes see it with binoculars, and you can see it with a telescope. Neptune is the 8th planet from the sun. It is 2.8 billion miles away from the sun, which is 30 times as far as Earth is from the sun (Earth is only the third planet from the sun). If you got on a spaceship it would take about 12 years to arrive.

The planet on the far right is Neptune, named after the Roman god of the sea because of its blue color.
Solar System

Size, Revolution, and Rotation

Neptune is the 4th largest planet. It is about 31,000 miles across. It would take around 60 Earths to fill up Neptune.

This picture shows the size of Neptune in relation to Earth
Neptune and Earth

It takes Earth 365 days, or one year, to revolve, or go around the sun. Believe it or not, it takes Neptune 165 years to travel around the sun! In fact, since the planet was discovered, in 1846, it has only gone completely around the sun once. Neptune spins very quickly though. It only takes about 16 hours for it to rotate (to turn completely around) one complete time. It takes Earth 24 hours to do the same thing.

Geography and Atmosphere

The Voyager 2 flew past Neptune in 1989. It gave astronomers many pictures and observations about its ring, moons, atmosphere, and rotation.
Neptune and Voyager 2

If you took a spaceship to Neptune you could not actually land on it, because it is made almost entirely out of the gases of hydrogen, helium, and methane. This portion of the planet is called its atmosphere. The methane is what gives the planet its blue color. It does have a rocky core at its center (which is about the size of Earth) made of nickel and iron.

Neptune has 14 moons that we know about, Triton being the largest one. The planet also has 5-6 thin rings made of dust and ice particles.

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