Andrew Yee[_1_]
June 20th 08, 02:54 PM
Science and Technology Facilities Council
Swindon, U.K.
Contacts
Julia Short
STFC Press Office
Tel: +44 (0)1793 442 012
Tom Stallard
University of Leicester
Tel: +44 (0)116 252 3589
Stan Cowley
University of Leicester
Tel: +44 (0)116 223 1331
18 June 2008
Spotlight on Saturn's Aurorae
A UK team of researchers have discovered a secondary aurora sparkling on
Saturn and also started to unravel the mechanisms that drive the process.
Their results are published in Nature (19 June 2008) and show that Saturn's
secondary aurora is much more like Jupiter's in origin than it is the
Earth's.
Aurorae are caused when charged particles stream along the magnetic field of
a planet and into its atmosphere. On Earth these charged particles come from
the solar wind -- a stream of particles that emanates from the Sun.
Variations in the Sun control the frequency and intensity of these beautiful
displays that can also herald problems -- such as interference with
satellite communications and power distribution.
On Jupiter however, the dominant source of particles is its own moons,
particularly Io which throws out roughly one tonne of volcanic material
every second. Some of this becomes ionised (plasma) and is pulled in
Jupiter's magnetic field. It co-rotates in a plasma sheet around the planet,
but as the particles spread out the magnetic field weakens and this breaks
down causing the particles to crash into Jupiter's atmosphere creating an
aurora.
On Saturn, whilst one aurora had been observed, the primary source of the
particles was unclear. RCUK Academic Fellow Tom Stallard, of the University
of Leicester explains: "At Saturn, scientists were unsure whether the aurora
was caused by the solar wind or by particles from its own system. When we
discovered the second zone of aurorae on Saturn, we realised this aurora,
unlike the one already seen on Saturn, was behaving in the same way as
Jupiter's, largely unaffected by the solar wind, dominated by the rotation
of the planet."
Modelling the aurorae on Jupiter and Saturn shows that both exhibit aurora
in the positions where the co-rotation between the planet and its plasma
sheet breaks down.
Stan Cowley of the University of Leicester said, "We can now say that some
of Saturn's aurorae are like Jupiter's and they have a common formation
process. Further, our discovery of the secondary aurora on Saturn suggests
that we shall also find one on Jupiter within its polar region."
This research is drawn from data collected by NASA's InfraRed Telescope
Facility. Saturn's main aurora has been studied using the NASA/ESA Hubble
Space Telescope.
The UK researchers have been funded by the Science and Technology Facilities
Council, the Engineering & Physical Sciences Research Council and Research
Councils UK.
Notes for Editors
Paper title: Jovian-like aurorae on Saturn
Authors: Tom Stallard [1], Steve Miller [2], Henrik Melin [3], Makenzie
Lystrup [2], Stan W H Cowley [1], Emma J Bunce [1], Nicholas Achilleos [2] &
Michele Dougherty [4]
[1] University of Leicester, Department of Physics and Astronomy, Leicester
LE1 7RH, UK
[2] University College London, Atmospheric Physics Laboratory, Department of
Physics and Astronomy, Gower Street, London WC1E 6BT, UK
[3] Space Environment Technologies, Planetary and Space Science Division,
320 N. Halstead Street, Suite 110, Pasadena, California 91107, USA
[4] Imperial College of Science, Technology and Medicine, Space and
Atmospheric Physics Group, Department of Physics, London SW7 2BW, UK
About STFC,
http://www.scitech.ac.uk/about/introduction.aspx
Swindon, U.K.
Contacts
Julia Short
STFC Press Office
Tel: +44 (0)1793 442 012
Tom Stallard
University of Leicester
Tel: +44 (0)116 252 3589
Stan Cowley
University of Leicester
Tel: +44 (0)116 223 1331
18 June 2008
Spotlight on Saturn's Aurorae
A UK team of researchers have discovered a secondary aurora sparkling on
Saturn and also started to unravel the mechanisms that drive the process.
Their results are published in Nature (19 June 2008) and show that Saturn's
secondary aurora is much more like Jupiter's in origin than it is the
Earth's.
Aurorae are caused when charged particles stream along the magnetic field of
a planet and into its atmosphere. On Earth these charged particles come from
the solar wind -- a stream of particles that emanates from the Sun.
Variations in the Sun control the frequency and intensity of these beautiful
displays that can also herald problems -- such as interference with
satellite communications and power distribution.
On Jupiter however, the dominant source of particles is its own moons,
particularly Io which throws out roughly one tonne of volcanic material
every second. Some of this becomes ionised (plasma) and is pulled in
Jupiter's magnetic field. It co-rotates in a plasma sheet around the planet,
but as the particles spread out the magnetic field weakens and this breaks
down causing the particles to crash into Jupiter's atmosphere creating an
aurora.
On Saturn, whilst one aurora had been observed, the primary source of the
particles was unclear. RCUK Academic Fellow Tom Stallard, of the University
of Leicester explains: "At Saturn, scientists were unsure whether the aurora
was caused by the solar wind or by particles from its own system. When we
discovered the second zone of aurorae on Saturn, we realised this aurora,
unlike the one already seen on Saturn, was behaving in the same way as
Jupiter's, largely unaffected by the solar wind, dominated by the rotation
of the planet."
Modelling the aurorae on Jupiter and Saturn shows that both exhibit aurora
in the positions where the co-rotation between the planet and its plasma
sheet breaks down.
Stan Cowley of the University of Leicester said, "We can now say that some
of Saturn's aurorae are like Jupiter's and they have a common formation
process. Further, our discovery of the secondary aurora on Saturn suggests
that we shall also find one on Jupiter within its polar region."
This research is drawn from data collected by NASA's InfraRed Telescope
Facility. Saturn's main aurora has been studied using the NASA/ESA Hubble
Space Telescope.
The UK researchers have been funded by the Science and Technology Facilities
Council, the Engineering & Physical Sciences Research Council and Research
Councils UK.
Notes for Editors
Paper title: Jovian-like aurorae on Saturn
Authors: Tom Stallard [1], Steve Miller [2], Henrik Melin [3], Makenzie
Lystrup [2], Stan W H Cowley [1], Emma J Bunce [1], Nicholas Achilleos [2] &
Michele Dougherty [4]
[1] University of Leicester, Department of Physics and Astronomy, Leicester
LE1 7RH, UK
[2] University College London, Atmospheric Physics Laboratory, Department of
Physics and Astronomy, Gower Street, London WC1E 6BT, UK
[3] Space Environment Technologies, Planetary and Space Science Division,
320 N. Halstead Street, Suite 110, Pasadena, California 91107, USA
[4] Imperial College of Science, Technology and Medicine, Space and
Atmospheric Physics Group, Department of Physics, London SW7 2BW, UK
About STFC,
http://www.scitech.ac.uk/about/introduction.aspx