All About Neptune

Depending on its orbital position, Neptune is often the eighth, sometimes the ninth planet from the sun. The planet Neptune is the smallest of our gas giants, or the planets in our solar system whose mass is primarily made up of gas. It is, like the other gas giants of Saturn, Jupiter and Uranus, without a well defined surface. Therefore, descriptions such as diameter and volume generally refer to the outermost layer.

Although Galileo first spotted Neptune in 1612, Urbain Le Verrier is credited with the official discovery on September 23rd, 1846. While Galileo believed Neptune to be a star, Verrier proved that it was in fact Neptune the planet. It is named after the Roman god of the Sea.

The composition of hydrogen, helium, and methane gives Neptune its unique blue color. It also has faint rings surrounding the planet. For many years, it was believed these rings were not complete. However, when the Voyager 2 reached the Neptune planet on August 25, 1989, their completion was confirmed. Nine moons have been documented in Neptune’s atmosphere, and 4 more are believed to be present.

Because of Pluto's strange orbit, Neptune is sometimes the most distant planet from the Sun. Since 1979, Neptune was the ninth planet from the Sun. On February 11, 1999, it crossed Pluto's path and once again become the eighth planet from the Sun, where will remain for 228 years.

Neptune data (averages):
Diameter: 30,775 miles
Time to rotate: 19 hours, 12 minutes
Orbit: 165 Earth years

Compared to Earth:
Mass: 17.2 times Earth's
Diameter: 3.9 times Earth's
Distance from Sun: 30 times as far

NEPTUNE: ROMAN GOD OF WATER
Historical notes

Neptune was discovered in 1846 after mathematical calculations of Uranus' movements predicted the existence of another large body.