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Neptune

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Neptune

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The smallest and most distant of the "gas giant" planets. Neptune has much in common with its three huge neighbors Jupiter, Saturn, and Uranus. It has strong winds, several light and dark spots on its surface, an internal heat source, rings, and moons. Neptune's Great Dark Spot is a storm about the size of the Earth.

Neptune's Mysterious Trail After Uranus was discovered in 1781, astronomers were able to track its orbit. They soon realized that the planet wasn't keeping the path they had predicted. Mathematicians figured out an explanation: the gravity of an unknown planet could be pulling Uranus off course. After calculating where such a planet would have to be, in 1846 German astronomer Johann Galle and Danish astronomer Heinrichd`Arrest saw Neptune for the first time.

Neptune's faint set of rings are probably made up of:

debris from Neptune's atmosphere

dust from the surface of Neptune's moons

comets

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Correct!

Neptune's four closest moons orbit between its rings. Triton, the largest moon, is bigger than the planet Pluto.

Frank Summers, astrophysicist

From the distance of Neptune, the Sun would appear to the human eye as no bigger than any other star in the sky, although it would overwhelmingly be the brightest.

In 2011, Neptune will complete its first orbit since it was discovered in 1846.

Fact
or
Fiction
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Fact

Neptune is thirty times farther from the Sun than the Earth, and orbits the Sun every 165 years.

Like the Earth, Neptune has a metal core.

Fact
or
Fiction
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Fiction

Neptune's core is made of rock, like the other "gas giant" planets. Neptune's rocky core is ten times more massive than the entire Earth.

Diameter: 31,000 miles
Location: 8th planet from Sun
Average Distance from the sun: 2.8 billion miles
First observed: 1846
Cloud Top Temperature: -300°F
Number of Moons: 8
Orbital Period: 165 years
Characteristics: gaseous blue planet with storms and winds reaching 400 miles per hour
Significance: 4th largest planet in solar system

Image credits: courtesy of JPL, California Institute of Technology and NASA; Frank Summers: AMNH.