Hi, I'm Dave Thurlow from the Mount Washington Observatory and this is The Weather Notebook. Today we're going to talk about a weather event that occurred on Jupiter recently.
Most people are familiar with Jupiter's Great Red Spot, a giant high-pressure region that spins counterclockwise in the Southern Hemisphere. In the late 1930's, white clouds filled a band to the south of the Great Red Spot. These clouds eventually broke up and formed into 3 spinning ovals of high pressure lined up in a row, each 2/3 the diameter of earth.
As of last Fall, astronomers still saw 3 ovals. Then, Jupiter went behind the sun and out of view, which it does every year. What's interesting is that when Jupiter reappeared in March, there were only 2 ovals, with one much larger than the other one. Scientists were baffled. The ovals had come close to each other in the past, but they always bounced off of each other like pool balls.
We aren't exactly sure how this happened, but there is a theory. The cause is believed to be similar to that of a 3-car accident, or a nice shot on a pool table. All three ovals moved around the planet at about 4 mph but for some reason, the first oval stopped moving. The last oval kept moving and bumped the oval in the middle into the stalled oval causing them to merge, forming a larger, earth-sized weather system.
The two remaining ovals are now moving away from each other and scientists hope that should they collide again, they'll be able to witness it.
For pictures and other information about the ovals on Jupiter, be sure to visit our website at weathernotebook.org. Our show is underwritten by Subaru, the beauty of all wheel drive with major support provided by the National Science Foundation.
Photo released by the Jet Propulsion Laboratory, Pasadena (USA).