Huge Saturn storm keeps surprising scientists
3 November BBC
A massive storm that encircled Saturn nearly two years ago was even
more powerful than scientists had thought, new research reveals.
Observations by NASA's Cassini spacecraft which first detected the
tempest in December 2010 show that the enormous Saturn storm sent
temperatures in the planet's stratosphere soaring 150 degrees Fahrenheit
(66 degrees Celsius) above normal, according to a new study.
"This temperature spike is so extreme it's almost unbelievable,
especially in this part of Saturn's atmosphere, which typically is very
stable," study lead author Brigette Hesman, of the University of
Maryland and NASA's Goddard Space Flight Center in Greenbelt, Md., said
in a statement.
"To get a temperature change of the same scale on Earth, you'd be
going from the depths of winter in Fairbanks, Alaska, to the height of
summer in the Mojave Desert," added Hesman, whose team describes its
results in a paper to be published in the Nov. 20 issue of The
Astrophysical Journal.
The team also detected a huge surge of ethylene at the time of the
storm, which apparently produced 100 times more of the odorless,
colorless gas than had been thought possible for Saturn. Its origin is a
mystery.
"We've really never been able to see ethylene on Saturn before, so
this was a complete surprise," said Goddard's Michael Flasar, team lead
for Cassini's composite infrared spectrometer instrument.
The monster Saturn storm was one of the planet's so-called Great
White Spots, which tend to pop up every 30 Earth years or so (or roughly
once every Saturn year). This most recent one grew to encircle the
planet by late January 2011, and it eventually extended about 9,000
miles (15,000 kilometers) from north to south before appearing to
sputter out in late June of that year.The tempest was the longest-lived
such storm ever observed on Saturn, scientists have said. And it was the
first one ever to be studied up-close by an orbiting spacecraft.
Cassini also observed two odd patches of warm air shining brightly in
the stratosphere during the storm, indicating a massive release of
energy into the planet's atmosphere.In a separate study appearing in the
journal Icarus, which looked at infrared data from Cassini and two
Earth-based telescopes, another research team describes how these two
patches merged to become the biggest and hottest stratospheric vortex
ever observed in our solar system. At first, this vortex was larger than
Jupiter's famous Great Red Spot.
Though visible signs of the Saturn storm are no longer evident, the
Saturn vortex persists to this day. But it's unlikely to have the
300-year-plus staying power of the Great Red Spot; scientists think the
vortex will likely dissipate by the end of 2013.
"These studies will give us new insight into some of the
photochemical processes at work in the stratospheres of Saturn, other
giants in our solar system, and beyond," said Scott Edgington, Cassini
deputy project scientist at NASA's Jet Propulsion Laboratory in
Pasadena, Calif.
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