Andrew Yee[_1_]
January 25th 07, 08:32 PM
Media Relations
University College London
London, U.K.
For further information, please contact:
Professor Alan Aylward
UCL Department of Physics & Astronomy
Tel: +44 (0)20 7679 2446
Judith H Moore
UCL Media Relations
Tel: +44 (0) 20 7679 7678
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.
University College London
London, U.K.
For further information, please contact:
Professor Alan Aylward
UCL Department of Physics & Astronomy
Tel: +44 (0)20 7679 2446
Judith H Moore
UCL Media Relations
Tel: +44 (0) 20 7679 7678
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.