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Big Weather at Jupiter: Cassini Snaps Earth-like Storms
By Robert Roy Britt
Senior Science Writer
posted: 07:00 am ET
02 January 2001
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In another finding made with instruments aboard Cassini, sulfur and oxygen spewed into space by the moon Io extend beyond Jupiter's magnetosphere. Scientists had thought the debris, known to be trapped into an orbiting plasma by the magnetic field, did not extend beyond the field.
Meanwhile, Cassini is creating new images of the magnetosphere that will further improve scientists' understanding of the enormous feature, scientists said last week.
Darwinian storms
On a planet where giant storms are the rule -- the Great Red Spot is almost twice the size of Earth and has been raging for more than 300 years -- smaller storms are like a farm system, playing a vital supporting role in feeding the big storms.
Planetary scientists have known for some years that Jupiter had lightning and that the large rotating cloud bands, as well as long-lived storms like the Great Red Spot, are kept alive by soaking up the energy of smaller storms. And last February, two separate reports in the journal Nature indicated that this energy welled up from below, much like large storms on Earth send their energy high into the atmosphere.
But so far, researchers have only been able to study snapshots of these storms. The Galileo spacecraft was not capable of returning enough data to generate storm movies covering several days. But Cassini has collected two months of data, said Andrew Ingersoll of the California Institute of Technology. So far, only 10 days of data have been processed.
The goal is to create a 60-day movie that would show "the entire birth and death of one of these thunderstorms -- how it forms, where it forms, and how it dies," Ingersoll told SPACE.com. Researchers expect that they will see a thunderstorm develop from below, gain rotational energy, and then transfer this energy into a larger storm.
Ingersoll says a better knowledge of storms on Jupiter will help in understanding Earth's atmosphere.
"The weather is different on Jupiter," Ingersoll said. "You have a 300-year-old storm. We'd like to know why Jupiter's weather is so stable, and Earth's is so transient."
Cassini passed about 6 million miles (9.7 million kilometers) above Jupiter last week in order to use the planet's gravity for a boost to take it to its main destination, Saturn, in 2004.
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