A giant storm rages in the northern hemisphere of Saturn in these two images from the Cassini spacecraft. The image at left shows the entire planet, with the rings forming a thin horizontal line across the middle. The storm is the billowing white feature at top center. It circles all the way around the giant planet. The image at right is a false-color close-up of a small part of the storm. Blue clouds are the highest, with yellow or white below them, then red and brown, and finally deep blue. The storm clouds probably are made of water ice covered by crystallized ammonia. [NASA/JPL/SSI]
Hurricane season is entering what's typically its most active time. Most of the tropical systems usually occur from late August through early October, with the peak in mid-September -- near the end of summer in the northern hemisphere.
An even bigger storm is starting to calm down on the planet Saturn. It began last December and has been raging ever since. At its peak, the storm wrapped all the way around the northern hemisphere.
Big storms aren't all that rare on Saturn. Beginning in 1876, a new one has been seen about every 30 years or so -- the length of the planet's orbit around the Sun. Until now, they've all started during early summer in the northern hemisphere.
But this storm came well ahead of schedule. It began in early spring. Here on Earth, it would be as if a Category 5 hurricane hit in April instead of during the warmer months of summer.
The storm began as a violent thunderstorm that pushed water and ammonia from hundreds of miles below the planet's visible cloudtops. As the giant plume hit the upper atmosphere, powerful winds sheared off the top, pushing the storm all the way around the giant planet.
The storm is calming down, but it may take a long time for the planet's northern hemisphere to return to normal.
Look for golden Saturn to the upper right of the Moon as night falls this evening. The star Spica is a little closer to the Moon's upper left. More about this lineup tomorrow.
Script by Damond Benningfield, Copyright 2011
For more skywatching tips, astronomy news, and much more, read StarDate magazine.