[meteorite-list] Jupiter: Turmoil from Below, Battering from Above

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 17 Oct 2012 13:11:50 -0700 (PDT)
Message-ID: <201210172011.q9HKBoEt024602_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?release=2012-328

Jupiter: Turmoil from Below, Battering from Above
Jet Propulsion Laboratory
October 17, 2012

Jupiter, the mythical god of sky and thunder, would certainly be pleased
at all the changes afoot at his namesake planet. As the planet gets
peppered continually with small space rocks, wide belts of the
atmosphere are changing color, hotspots are vanishing and reappearing,
and clouds are gathering over one part of Jupiter, while dissipating
over another. The results were presented today by Glenn Orton, a senior
research scientist at NASA's Jet Propulsion Laboratory, Pasadena,
Calif., at the American Astronomical Society's Division for Planetary
Sciences Meeting in Reno, Nev.

"The changes we're seeing in Jupiter are global in scale," Orton said.
"We've seen some of these before, but never with modern instrumentation
to clue us in on what's going on. Other changes haven't been seen in
decades, and some regions have never been in the state they're appearing
in now. At the same time, we've never seen so many things striking
Jupiter. Right now, we're trying to figure out why this is all happening."

Orton and colleagues Leigh Fletcher of the University of Oxford,
England; Padma Yanamandra-Fisher of the Space Science Institute,
Boulder, Colo.; Thomas Greathouse of Southwest Research Institute, San
Antonio; and Takuyo Fujiyoshi of the Subaru Telescope, National
Astronomical Observatory of Japan, Hilo, Hawaii, have been taking images
and maps of Jupiter at infrared wavelengths from 2009 to 2012 and
comparing them with high-quality visible images from the increasingly
active amateur astronomy community. Following the fading and return of a
prominent brown-colored belt just south of the equator, called the South
Equatorial Belt, from 2009 to 2011, the team studied a similar fading
and darkening that occurred at a band just north of the equator, known
as the North Equatorial Belt. This belt grew whiter in 2011 to an extent
not seen in more than a century. In March of this year, that northern
band started to darken again.

The team obtained new data from NASA's Infrared Telescope Facility and
the Subaru Telescope on Mauna Kea that matched up that activity with
infrared observations. Those data showed a simultaneous thickening of
the deeper cloud decks, but not necessarily the upper cloud deck, unlike
the South Equatorial Belt, where both levels of clouds thickened and
then cleared up. The infrared data also resolved brown, elongated
features in the whitened area called "brown barges" as distinct features
and revealed them to be regions clearer of clouds and probably
characterized by downwelling, dry air.

The team was also looking out for a series of blue-gray features along
the southern edge of the North Equatorial Belt. Those features appear to
be the clearest and driest regions on the planet and show up as apparent
hotspots in the infrared view, because they reveal the radiation
emerging from a very deep layer of Jupiter's atmosphere. (NASA's Galileo
spacecraft sent a probe into one of these hotspots in 1995.) Those
hotspots disappeared from 2010 to 2011, but had reestablished themselves
by June of this year, coincident with the whitening and re-darkening of
the North Equatorial Belt.

While Jupiter's own atmosphere has been churning through change, a
number of objects have hurtled into Jupiter's atmosphere, creating
fireballs visible to amateur Jupiter watchers on Earth. Three of these
objects - probably less than 45 feet (15 meters) in diameter - have been
observed since 2010. The latest of these hit Jupiter on Sept. 10, 2012,
although Orton and colleagues' infrared investigations of these events
showed this one did not cause lasting changes in the atmosphere, unlike
those in 1994 or 2009.

"It does appear that Jupiter is taking an unusual beating over the last
few years, but we expect that this apparent increase has more to do with
an increasing cadre of skilled amateur astronomers training their
telescopes on Jupiter and helping scientists keep a closer eye on our
biggest planet," Orton said. "It is precisely this coordination between
the amateur-astronomy community that we want to foster."

The California Institute of Technology, Pasadena, operates the Jet
Propulsion Laboratory for NASA.

Jia-Rui Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jccook at jpl.nasa.gov

2012-328
Received on Wed 17 Oct 2012 04:11:50 PM PDT