Cassini makes simultaneous measurements of Saturn's nightside aurora and electric current system

March 27, 2012
Two images of Saturn’s northern auroral oval, made with the Ultraviolet Imaging Spectrometer (UVIS) instrument. The second image, made two hours after the first, shows the motion of the oval as the planet rotates. Credit: NASA / ESA and the Cassini UVIS team

(PhysOrg.com) -- Since the NASA / ESA Cassini-Huygens spacecraft arrived at Saturn in 2004, astronomers and space scientists have been able to study the ringed planet and its moons in great detail. Now, for the first time, a team of planetary scientists have made simultaneous measurements of Saturn’s nightside aurora, magnetic field, and associated charged particles. Together the fields and particle data provide information on the electric currents flowing that produce the emissions. Team leader Dr Emma Bunce of the University of Leicester will present the new work at the National Astronomy Meeting in Manchester on 27 March 2012.

Generally, images of the (equivalent to the terrestrial ‘northern lights’) provide valuable information about the electromagnetic connection between the solar wind, the planet’s magnetic field () and its upper atmosphere. Variations in the aurora then provide information on changes in the associated magnetosphere. But viewing the aurora (best done at a large distance) at the same time as measuring the magnetic field and charged particles at high latitudes (where the aurora is found, best done close to the planet) is hard

In 2009, Cassini made a crossing of the magnetic field tubes that connect to the aurora on the night side of Saturn. Because of the position of the spacecraft, Dr Bunce and her team were able to obtain ultraviolet images of the aurora (which manifests itself as a complete oval around each pole of the planet) at the same time.

This is the first time it has been possible to make a direct comparison between Cassini images of the nightside aurora and the and particle measurements made by the spacecraft. And because of the geometry of the orbit at Cassini, it took about 11 hours to pass through the high-latitude region or about the same time it takes Saturn to make one rotation.

This meant that the team were able to watch the auroral oval move as the planet turned. As Saturn and its magnetosphere rotated, the auroral oval was tilted back and forth across the spacecraft with a speed that is consistent with a planetary rotation effect:

Dr Bunce comments: “With these observations we can see the simultaneous motion of the electric current systems connecting the magnetosphere to the atmosphere, producing the aurora. Ultimately these observations bring us a step closer to understanding the complexities of ’s magnetosphere and its ever elusive rotation period”.

Explore further: Cassini captures new views of Saturn's aurora (w/ Video)

Related Stories

New Cassini Images Show "Northern Lights" Of Saturn

August 4, 2005

New images of Saturn obtained by a University of Colorado at Boulder-led team on June 21 using an instrument on the Cassini spacecraft show auroral emissions at its poles similar to Earth's Northern Lights.

Discovery of Saturn's auroral heartbeat

August 4, 2010

(PhysOrg.com) -- An international team of scientists led by Dr Jonathan Nichols of the University of Leicester has discovered that Saturn’s aurora, an ethereal ultraviolet glow which illuminates Saturn’s upper atmosphere ...

Recommended for you

Gaia turns its eyes to asteroid hunting

January 24, 2017

While best known for its surveys of the stars and mapping the Milky Way in three dimensions, ESA's Gaia has many more strings to its bow. Among them, its contribution to our understanding of the asteroids that litter the ...

Dwarf galaxies shed light on dark matter

January 23, 2017

The first sighting of clustered dwarf galaxies bolsters a leading theory about how big galaxies such as our Milky Way are formed, and how dark matter binds them, researchers said Monday.

One of the brightest distant galaxies known discovered

January 23, 2017

An international team led by researchers from the Instituto de Astrofísica de Canarias (IAC) and the University of La Laguna (ULL) has discovered one of the brightest "non-active" galaxies in the early universe. Finding ...

Image: Wavemaker moon Daphnis

January 20, 2017

The wavemaker moon, Daphnis, is featured in this view, taken as NASA's Cassini spacecraft made one of its ring-grazing passes over the outer edges of Saturn's rings on Jan. 16, 2017. This is the closest view of the small ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.