Lawrence Sromovsky (University of Wisconsin-Madison), NASA/Space Telescope Science Institute

A time-lapse animation of the rotation of Neptune has been assembled from images taken by NASA's Hubble Space Telescope and the Infrared Telescope Facility on Mauna Kea, Hawaii. By observing the planet at different wavelengths, astronomers see different levels of the atmosphere. These images show Neptune's storms, dark spots, and its powerful equatorial jet stream.

Neptune's atmosphere

Neptune's atmosphere was first revealed to us when Voyager flew by the planet in 1989. Since then, the Hubble Space Telescope has provided scientists with more detailed views of the cloud structure and dynamics. Some features of the atmosphere include dark spots, methane cloud tops, and a complex circulatory system. The northern dark spot, discovered using the Hubble in 1995, may be a hole in the methane cloud tops, allowing one to see deeper into the atmosphere. As the air in the atmosphere flows over the spot, the particles condense to form methane ice crystal clouds. Neptune's equatorial jet stream is not driven by the Sun as it is on Earth, but is driven by an internal energy source. Neptune radiates about twice as much energy as it receives from the Sun. This energy may warm the clouds triggering the atmospheric circulation we observe.

Ellen Cohen