Talk about mistaken identity! When the planet Neptune was first seen, the astronomer who saw it thought it was a star. And when astronomers found out what Neptune really was, it was because they were studying another planet. We still have a lot to learn about Neptune, but here’s some of what we know so far:

Q: How was Neptune discovered?
A: Neptune was first seen in 1613, by Galileo Galilei, a scientist from Italy. He only saw the planet for two nights, and wasn’t able to find out much about it. Because of this, he thought it was a star instead of a planet. Neptune had to wait almost 200 years for someone to discover what it really was. Astronomers were actually studying another planet, Uranus. They noticed that Uranus didn’t behave the way they expected it to. The only reason they could think of was that there was another planet nearby. This planet must be having an effect on how Uranus moved. So, two different mathematicians, who were working on the problem separately, tried to figure out where this unknown planet could be. By studying other planets in the same area, they used math to predict where this other planet was. Astronomer Johann Galle found the planet in 1846, very close to where the two mathematicians said it would be. (The two mathematicians, John Couch Adams and Urbain Leverrier, became good friends.)

Q: How big is Neptune?
A: It is the fourth-largest planet in our solar system, and is about 17 times as big as Earth. Neptune is about 31,000 miles in diameter. However, it is the smallest of the “gas giants,” a group of planets that includes Jupiter, Saturn and Uranus. This group got its nickname because none of the planets have any solid surfaces.

Q: How far away is Neptune?
A: Neptune is about 2.7 million miles away from the Sun, and is about 30 times farther from the Sun than Earth is. It is the eighth planet from the Sun, but sometimes its neighbor, Pluto, crosses into its path. When this happens, Neptune becomes the farthest planet from the Sun. This happens every 248 years, and lasts for 20 years.

Q: Is it hot or cold on Neptune?
A: It is very cold on Neptune. About -370 degrees Fahrenheit, in fact. (I knew I should have brought my jacket!)

Q: Why is Neptune blue?
A: Neptune’s atmosphere contains methane, a gas. When red light is absorbed by the methane, it creates a blue color.

Q: Does Neptune have any moons?
A: Neptune has 13 moons that we know of. The largest one is Triton, which is made of rock and ice.






Neptune

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