Astronomy Skylights Podcast: Neptune

by ANDY FLEMING

Neptune, the solar system's furthest planet from the Sun. The colour of its thick atmosphere is due to its constituents: mainly hydrogen, helium and methane.

As featured on 102.4 Radio Hartlepool's Solid Gold Sunday with Andy Fleming

Podcast available here 

Full show available here

For most of human civisilisation humans were unaware that Neptune even existed. It was discovered by Johann Galle and Heinrich D'Arrest in 1846. It’s the smallest of the four gas giants in our Solar System. Much like Saturn and Uranus, Neptune's atmosphere contains hydrogen, helium and methane.

Not much was known about the planet until it was visited by the spacecraft Voyager 2 on August 25, 1989 which took many photographs. These show a brilliant blue planet with a few thin white clouds laced around its surface. In Neptune's atmosphere, there is a large white cloud that moves around rather quickly. The "scooting" of this cloud around the atmosphere has led it to be named "Scooter."

Voyager 2’s data also showed a giant storm much like the storm on Jupiter. This storm is called the "Great Dark Spot" because it appears as a dark oval shape on the surface of the planet. We do not know how long this storm has been active or if it is still present. More recently, the Hubble Space Telescope sent pictures back to Earth and there was no sign of the Great Dark Spot. These pictures did show two other dark spots that eventually faded away.

Neptune is the windiest place in the solar system with winds near the Great Dark Spot reaching nearly 1,200 miles per hour. Perhaps this extremely windy atmosphere contributes to the appearance and disappearance of its atmospheric features.

Neptune has six rings which encircle the planet that are thought to be fairly new, and are more irregular than the rings of other planets. It has 13 moons, the largest of which is Triton, thought to be a captured asteroid.