Neptune for Kids
Planet 8 from the Sun
Neptune is the eighth planet from the Sun. Its day lasts 16.1 hours. Its year lasts 164 Earth years. That is from NASA's planetary fact sheet, checked 29 October 2026. A scale there reads 1.12 times as much as on Earth. Read about it at three levels: Little, Middle and Big, and make your own Space Card.
Neptune is a deep blue planet, the farthest from the Sun. It is cold and very, very windy.
Neptune has the fastest winds of any planet, over 2,000 kilometers an hour. It is so far away that one trip round the Sun takes about 165 Earth years. Telescopes found it in 1846 after math pointed to where it should be.
Neptune is an ice giant, 30 times farther from the Sun than Earth, with a mean temperature near minus 200 degrees Celsius. Astronomers calculated where an unseen planet had to be from the wobble in Uranus's orbit, then found Neptune there.
Neptune was found with math before anyone saw it.
Neptune in numbers
| Across | 49,528 km |
|---|---|
| From the Sun | 4515 million km |
| A day | 16.1 hours |
| A year | 164 Earth years |
| Pull of gravity | 1.12 times Earth's |
| Average temperature | -200 °C |
| Moons | 16 |
Source: NASA planetary fact sheet, checked 29 October 2026.
How big is Neptune?
Neptune is 49,528 kilometers across, 3.9 Earths wide. Neptune is 4.51 billion kilometers from the Sun, on average.
How hot or cold is Neptune?
Neptune averages -200 degrees Celsius, far colder than any freezer on Earth.
Does Neptune have moons?
Neptune has 16 moons by NASA's count, and the number can grow as telescopes find more.
Can I see Neptune tonight?
Not with your eyes. It is far too faint; you need a telescope and a map. Sky Tonight gives your own times from a ZIP.
How much would I weigh on Neptune?
A child who weighs 80 pounds on Earth would read 90 pounds on Neptune. That is a game number: it only shows how hard Neptune pulls compared with Earth. Make your own Space Card to guess first and see all eleven worlds.