Neptune

Neptune is the fourth largest of the planets in the solar system and eighth major planet in order of increasing distance from the Sun. It is similar in size and structure to its neighbour Uranus. Neptune is, on average, about 4.5 billion km (2.8 billion miles) from the sun. It is about 49,400 km (30,700 miles) in diameter, or about 3.8 times as wide as the earth. Even though Neptune's volume is 72 times that of Earth's, its mass is only 17 times Earth's mass.