Neptune information for kids

Learn about the solar systems eighth planet from the sun and why Neptune always appears blue.

Photo Credit: NASA
By Lindsey Hadwin

Neptune is the eighth planet from the Sun. However, every couple hundred years, Pluto’s orbit brings it closer, making Neptune the ninth planet from the Sun momentarily. The last time this happened was in 1979. Pluto stayed the eighth planet in the solar system for 20 years, until its orbit bypassed Neptune in 1999. This event won’t happen again for another 242 years.

Neptune is also the fourth largest planet in the solar system, big enough to fit 60 Earths inside!

Neptune is approximately 3 billion miles from the Sun and it takes about 165 years for Neptune to orbit the Sun once—meaning that one year on Neptune is equivalent to 165 Earth years! A Neptune day is only 16 hours, however, which means that the planet rotates fairly quickly.

Neptune may be the windiest planet in our solar system, often having winds that reach over 1,200 miles per hour. The winds are so strong, that at one time Neptune’s Great Dark Spot was blown across the planet at 700 miles per hour. The dark spot is about the same size as Earth. These strong winds are a result of the planet’s speed of rotation and the vast temperature differences on the planet.

Neptune’s blue appearance comes from the layer of methane gas that sits above the clouds. Methane absorbs red light, so only the bluish colors show up when viewing the planet.

Much is still unknown about Neptune, because the strong pressure makes it impossible for us to land on the planet. It is thought that there is an ocean of really hot water on Neptune’s surface. The planet’s pressure makes it impossible for the water to boil away.

The only spacecraft to visit Neptune was the Voyager 2 in 1989. Voyager confirmed that Neptune’s atmosphere was very cold and very windy. In fact, the surface of Neptune reaches 200 degrees below zero! Regardless of the frigid temperatures, Neptune’s core remains very warm. Neptune actually gives off more heat than it receives from the Sun.

The giant blue planet has four rings and at least thirteen moons. The largest of Neptune’s moons, Triton, is colder than Pluto. Triton also has geysers that originate deep inside the moon. These geysers give off eruptions of nitrogen gas.

Neptune’s four rings are named Adams, Galatea, Le Verrier and Galle. The rings are made up of dust particles that are probably a result of small meteorites that have smashed into Neptune’s moons.

Neptune was discovered by Johann Gottfried Galle of the Berlin Observatory in 1846. Two years earlier, the presence of the planet was predicted based on the locations of the other planets in the solar system. The planet was found to be within 1 degree of the predicted location. The prediction was made by French astronomer Urbain Jean Le Verrier.

It has been found that the most of Neptune is composed of molten rock, water, methane and liquid ammonia. The outer edge of the planet is composed of a mix of gases, included helium, water, methane and hydrogen.