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Dark, cold and whipped by supersonic winds, giant Neptune is the eighth and most distant major planet orbiting our Sun.

More than 30 times as far from the Sun as is Earth, Neptune is not visible to the naked eye. Neptune was the first planet located using math.

Galileo recorded Neptune as a fixed star during observations with his small telescope in 1612 and 1613.

More than 200 years later, the ice giant became the first planet located through mathematical predictions rather than through observations of the sky. In 1989, NASA's Voyager 2 became the first -and only - spacecraft to study Neptune up close.

Neptune has 16 known moons.

English merchant and astronomer William Lassell discovered the first and largest of Neptune's moon – Triton – on Oct. 10, 1846, just 17 days after a Berlin observatory discovered Neptune.

In 1989, NASA's Voyager 2 became the first-and only-spacecraft to study Neptune up close. Voyager returned a wealth of information about Neptune and its moons-and confirmed evidence the giant world had faint rings like the other gas planets.

Neptune is the eighth and most distant planet in our solar system.

Dark, cold, and whipped by supersonic winds, ice giant Neptune is more than 30 times as far from the Sun as Earth. Neptune is the only planet in our solar system not visible to the naked eye. In 2011 Neptune completed its first 165-year orbit since its discovery in 1846.

Neptune is so far from the Sun that high noon on the big blue planet would seem like dim twilight to us. The warm light we see here on our home planet is roughly 900 times as bright as sunlight on Neptune.

Galileo recorded Neptune as a fixed star during observations with his small telescope in 1612 and 1613. More than 200 years later, the ice giant became the first planet located through mathematical predictions rather than through regular observations of the sky. Because Uranus didn't travel exactly as astronomers expected it to, French mathematician Urbain Joseph Le Verrier proposed the position and mass of a then-unknown planet that could cause the observed changes to Uranus' orbit. Le Verrier sent his predictions to Johann Gottfried Galle at the Berlin Observatory, who found Neptune on his first night of searching in 1846. Seventeen days later, Neptune's largest moon Triton was discovered as well.

Neptune's environment is not conducive to life as we know it. The temperatures, pressures, and materials that characterize this planet are most likely too extreme, and volatile for organisms to adapt to.

With an equatorial diameter of 30,775 miles (49,528 kilometers), Neptune is about four times wider than Earth. If Earth were the size of a nickel, Neptune would be about as big as a baseball.

Neptune has 16 known moons. English merchant and astronomer William Lassell discovered the first and largest moon – Triton – on Oct. 10, 1846, just 17 days after a Berlin observatory discovered Neptune.

We don't know if Lassell had a celebratory beverage after he discovered Triton, but beer helped make the finding possible. Lassell was one of 19th century England's grand amateur astronomers. He used the fortune he made in the brewery business to finance his telescopes.

All but two of Neptune's 16 moons have been named. Since Neptune is named for the Roman god of the sea, its moons are named for various lesser sea gods and nymphs in Greek mythology.