Guide to the planets…Neptune

Wizard's Eye, the smaller storm that looks lik...

Fact file

  • 8th planet from the sun (distance from the sun: 2, 795, 084, 800 miles)
  • Neptune has a large storm raging on its surface known as the great dark spot (similar to Jupiter’s great red spot)
  • gas giant atmosphere containing hydrogen, helium and methane
  • average surface temperature: -214 degrees C
  • length of year: 60, 190 days
  • length of day: 16 hours  7 minutes
  • number of moons: 13

 Neptune is the 8th planet from the sun and is the only planet that cannot be seen by the naked eye. This is because of its sheer distance from earth and the sun.  Neptune is the smallest of the gas giant’s and has a similar atmosphere to Uranus, made up of hydrogen, helium and methane. The methane in Neptune’s atmosphere is the reason for the blue colour of the planet, similar to Uranus’ blue-green appearance. However, it is unknown why Neptune is such a bright blue colour and not a more blue-green colour. It has been suggested that Neptune’s atmosphere has another currently unknown component that could result in only blue light being reflected back to us.

Neptune’s atmosphere is home to winds that are three times stronger than Jupiter’s’ and up to 9 times stronger that those on Earth.  In 1989, Voyager 2 observed a large dark storm in Neptune’s Southern hemisphere. this storm span anticlockwise and was large enough to engulf the whole of planet Earth.  this storm travels in a westerly direction across the planet at 750 miles per hour, and has been given the name of the Great dark spot, a similar name to the larger storm on Jupiter called the great red spot.

Neptune has 6 rings which were also discovered by Voyager 2 in 1989. These rings vary in thickness and are thought to be relatively young and short-lived. Neptune also has at least 13 moons which orbit it. The largest moon is called Triton and , unusually, orbits in the opposite direction to the planet’s rotation.  This moon has a surface temperature of -235 degrees C, making it the coldest body visited so far in our solar system.  Triton has geysers that throw icy particles 5 miles upwards. Also, Triton has a thin atmosphere which is growing warmer, although it is unclear why this is.  Another of Neptune’s moons is called Nereid and is one of the farthest orbiting moons from Neptune.  Due to this large distance from its parent planet, Nereid takes around 360 days to complete one full orbit of Neptune.