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Neptune




Symbol
Diameter49532 km, 3.89 x Earth's
Mass17.2 ME
Volume54 VE
Mean Density1.76 g/cm3
Mean Distance from Sun4497 x 106km = 30.058 AU
Eccentricity of Orbit0.009
Inclination of Equator to Orbit28°
Inclination of Orbit to Ecliptic
ColourBlue
Temperature-180°C
AtmosphereHydrogen, helium and methane
Length of Day16.1 hours
Length of Year165 years
No. of Moons8
Gravity1.194 x Earth's
Escape Velocity24.6 km/s
Albedo0.41



Neptune is the eighth planet in the Solar System, and the last of the gas giants. It was discovered in 1846 after observations of Uranusí orbit showed that wasnít moving in quite the way it should. Scientists concluded that another planet must be pulling on Uranus, and so started the search for Neptune. Neptune's Great Dark Spot

Neptune looks blue because, like on Uranus, the methane in the atmosphere absorbs all of the red light. Therefore the blue light from the Sun is reflected, but the red light is absorbed, causing the planet to appear blue. The planet also has a dark spot, which is a huge storm in the atmosphere, similar to Jupiter's Great Red Spot.

Neptune was actually the furthest planet from the Sun between 1979 and February 1999 because Plutoís orbit is so elliptical that it sometimes passes within Neptune's. Clouds in Neptune's atmosphere

Neptune has rings like those of Saturn made of dust and small pieces of rock. They are much harder to see than Saturnís because they are made of a much darker material that doesnít reflect the Sunís light so well.

Neptune has the fastest winds in the Solar System, reaching speeds of 2000 kph.





Planets Introduction

Mercury

Venus

Earth

The Moon

Mars

Jupiter

Saturn

Uranus

Pluto

Asteroids

Comets

Meteorites

Extra-Solar Planets



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Authors: Carolyn Brinkworth and Claire Thomas

Last updated: July 2001