Exploring the Planets

Neptune's Atmosphere

Clouds of Blue

Neptune's atmosphere is made up of hydrogen, helium, and methane. Like Earth's atmosphere, Neptune's has clouds and storm systems that revolve around the planet, but with wind speeds of 300 m/sec (700 mi/hr), and clouds of frozen methane.

The "Great Dark Spot" discovered by Voyager 2 is a huge storm system that resembles Jupiter's Red Spot, and is surrounded by white cirrus clouds of frozen methane. More recent views of Neptune from the Hubble Space Telescope show no signs of the Spot, indicating that it has vanished over the years.

 

Neptune Full Disk View

Changes In Cloud Structure

These images of the Great Dark Spot were taken by Voyager 2 over a 4 1/2 day period at intervals of 18 hours. As shown on the left, a "tail" of the dark spot separated into individual spots that moved westward. The Great Dark Spot may have an overall counterclockwise rotation as suggested by the lighter toned clouds surrounding the main spot.

 

Neptune's Great Dark Spot

Changes In Cloud Structure

Voyager 2 imaged other atmospheric features as well. In this image, a bright spot nicknamed "Scooter" lies south of the Great Dark Spot, and beneath that is a feature known as "Dark Spot 2".

 

Neptune Scooter