Unexpected cooling effect in Saturn's atmosphere found (Forwarded)

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Judith H Moore
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24 January 2007

Unexpected cooling effect in Saturn's atmosphere found

In the hunt for interplanetary answers to how atmospheric temperatures are
maintained, UCL researchers have ruled out a long held theory. They've
found that the hotter than expected temperature of Saturn's upper
atmosphere -- and that of the other giant planets -- isn't due to the same
mechanism that heats the atmosphere around the Earth's Northern Lights.

A simple calculation to give the expected temperature of a planet's upper
atmosphere balances the amount of sunlight absorbed by the energy lost to
the lower atmosphere. But the calculated values don't tally with the
actual observations of the Gas Giants: they are consistently much hotter.

It has long been thought that motion within the electrically charged part
of the atmosphere, the ionosphere, is driven by the planet's magnetic
field, or magnetosphere, was the culprit behind this heating process. Now
writing in the journal Nature, the researchers reveal, using numerical
models of Saturn's atmosphere, that the net effects of the winds driven by
polar energy inputs is not to heat the atmosphere but actually cools it.

Professor Alan Aylward, of the UCL Department of Physics & Astronomy, and
an author of the study, explains: "The aurora has been studied for over a
hundred years, yet our discovery takes us back to first principles. We
need to re-examine our basic assumptions about planetary atmospheres and
what causes the observed heating."

"Studying what happens on planets such as Saturn gives us an insight into
what happens closer to home. Planets can lose their atmospheres as we see
with Mars. Do we completely understand how this happens? Are there
mechanisms heating the gas and causing it to escape that we do not yet
fully understand? By studying what happens in other atmospheres we may
find clues to Earth's future."

The study was funded by the UK Particle Physics and Astronomy Research
Council (PPARC) and Sun Microsystems Ltd.

-end-

Notes to editors

The paper 'An unexpected cooling effect in Saturn's upper atmosphere' is
published in the January 25th edition of the journal Nature. C. G. A.
Smith [1], A. D. Aylward [1], G. H. Millward [1{, S. Miller [1] & L. E.
Moore [2]

[1] Department of Physics and Astronomy, University College London, WC1E
6BT, UK.
[2] Center for Space Physics, Boston University, Boston, Massachusetts
02215, USA.
{Present address: Laboratory for Atmospheric and Space Physics, University
of Colorado, Boulder, Colorado 80303, USA.

Whatever happened with the giant hurricane-like storm spotted at the
South
pole on Nov 9, 2006? Hurricanes on Saturn run for a full day's orbit or
so after forming when at the equator. The whirlpool at the South pole
of Saturn was stuck in position and the upper atmosphere warmed 2
degrees near the South pole at the time, apparently inner heat escaping
and the cooler clouds at the top making it inside the whirlpool
phenomena. Saturn rotates very fast (once every 10 hours) and is an
Earth diameter wider than its height. The fast rotation could cause
sudden changes of weather.

wrote:

Whatever happened with the giant hurricane-like storm spotted at the
South
pole on Nov 9, 2006?

http://saturn.jpl.nasa.gov/multimedi...m?imageID=2462

On Jan 26, 2:24 am, Michael Sandell
wrote:
wrote:
Whatever happened with the giant hurricane-like storm spotted at the
South
pole on Nov 9, 2006?http://saturn.jpl.nasa.gov/multimedi...ils.cfm?imageI...

That may make sense: If the upper layers of the gasses are warmer in
Saturn then
expected, then the warm may move toward cold, or toward the South Pole.
Weird because one expects the upper gasses to be colder normally, and
the gasses at the South Pole are closer to the planet's inner heat
because Saturn is wider than its height by a great distance. Just a
puzzle why there is that bullseye hwirl. Thanks for the info.