Sunday Science: Neptune

An image of Neptune, taken by the Voyager 2 spacecraft. NASA - JPL image.

Neptune is the furthest planet from the Sun - but it may have formed much closer to the Sun before moving to its present position.

Neptune rotates on its axis incredibly quickly - its equatorial clouds take only 18 hours to make one rotation - and it's also the smallest of the class of planets known as the "ice giants". Despite being smaller than Uranus, Neptune has a greater mass.

It also has a very thin collection of rings and has 14 moons. One moon, Triton, is a volcanic icy world and was recently discovered to have seasons.

Mosaic of Triton, taken by Voyager 2 in 1989. Credit: NASA/JPL/USGS

Why is Neptune so blue?

Neptune's atmosphere is made up of hydrogen, helium and methane gases. Methane absorbs red light, so the planet has a rich blue hue. Below its atmosphere, you'd find a layer of water, ammonia and methane ice and the inner core is made up of rock.

The planet also has a very active climate. A large storm was recorded on its surface in 1989 (and can be seen in the above image) - it was called the Great Dark Spot and lasted approximately five years. 

The Great Dark Spot was discovered by the Voyager 2 spacecraft, which is the only craft to have flown by the planet. The Hubble Space Telescope has also studied Neptune, as have many ground-based telescopes. In fact, a strange storm that's as wide as the Earth has recently been spotted on Neptune by the Keck Observatory in Hawaii.

The size of Neptune, compared to the Earth. From http://space-facts.com/neptune/.

Extra reading and watching

Believe it or not, scientists have theorised that Neptune and Uranus could produce "diamond rain" thanks to the combination of the high temperatures and pressures, and the hydrocarbons present on both planets.

It may sound a bit far-fetched, but this process has recently been reproduced in the lab. Unfortunately, the lab-produced diamonds were only a few nanometres thick - but Neptune and Uranus's diamonds could be far bigger.

And here's a great video on the blue planet from Astrum:

What is Sunday Science?

Hello. I’m the freelance writer who gets tech. I have two degrees in Physics and, during my studies, I became increasingly frustrated with the complicated language used to describe some outstanding scientific principles. Language should aid our understanding — in science, it often feels like a barrier.
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So, I want to simplify these science sayings and this blog series “Sunday Science” gives a quick, no-nonsense definition of the complex-sounding scientific terms you often hear, but may not completely understand. 

If there’s a scientific term or topic you’d like me to tackle in my next post, fire an email to [email protected] or leave a comment below. If you want to sign up to our weekly newsletter, click here.