Stunning video of Saturn’s auroras from Leicester-led observations
Published by University of Leicester Press Office for University of Leicester in Education
University of Leicester scientists have led work on a set of stunning images of Saturn’s auroras.
The Earth’s northern lights amazed viewers of Stargazing Live earlier this month – and now, aurora lovers can see an awe-inspiring selection of views of extra terrestrial polar phenomena.
A spectacular set of views of the dancing lights at Saturn's poles can be found on a striking new video on NASA’s YouTube website at: http://www.youtube.com/watch?v=p32xzRSBXuk
The images come from an international observational campaign of Saturn, part of which was led by Dr Jonathan Nichols, of the University of Leicester’s Department of Physics and Astronomy, in April and May last year.
Images were taken using NASA's Hubble Space Telescope, which orbits the Earth and was able to observe Saturn’s northern auroras in ultraviolet wavelengths – as well as NASA's Cassini spacecraft, from its orbit around Saturn.
Cassini was able to get complementary close-up views of the north and south on parts of Saturn that don't face Earth, in infrared, visible-light and ultraviolet wavelengths.
The images from both sources give a step-by-step choreography detailing how the auroras move, showing the complexity of these auroras and how scientists can connect an outburst from the sun and its effect on the magnetic environment at Saturn.
"Saturn's auroras can be fickle – you may see fireworks, you may see nothing," said Dr Jonathan Nichols. "In 2013, we were treated to a veritable smorgasbord of dancing aurora, from steadily shining rings to super-fast bursts of light shooting across the pole."
"The Earth's northern lights are not just a spectacular natural light show, they reveal the intimate relationship between our planet's magnetic field and a million mile-per-hour stream of charged particles emitted by the Sun.
“This solar wind also lights up auroras at the outer planets, and Saturn's auroras similarly reveal how that planet's magnetic field responds to a buffeting by solar storms.
“Saturn's auroras are particularly spectacular since, from our vantage point at Earth, we are treated to a wonderful view of the entire polar region, and the illuminations can evolve dramatically as we watch, revealing the magnetic turmoil surrounding the planet."
Images from Cassini's ultraviolet imaging spectrometer (UVIS), obtained from an unusually close range of about six Saturn radii, provided a look at the changing patterns of faint emissions on scales of a few hundred miles and tied the changes in the auroras to the fluctuating wind of charged particles blowing off the sun and flowing past Saturn.
The UVIS images also suggest the bright auroral storms may be produced by the formation of new connections between magnetic field lines, a process that causes storms in the magnetic bubble around Earth, although other processes have also been suggested.
The video also shows one persistent bright patch of the aurora rotating in lockstep with the orbital position of Saturn's moon Mimas.
While previous UVIS images have shown an intermittent auroral bright spot magnetically linked to the moon Enceladus, the video suggests another Saturn moon can influence the light show as well.
The new data give scientists clues to a long-standing mystery about why the atmospheres of Saturn and other gas giants are heated far beyond what might normally be expected by their distance from the sun.
The results show where the aurora heats the atmosphere of gas giants as the particles dive into it and how long the “cooking” occurs.
Cassini's visible-light data have helped scientists figure out the colors of Saturn's auroras. While the curtain-like auroras we see at Earth are green at the bottom and red at the top, Cassini's imaging cameras have shown us similar curtain-like auroras at Saturn that are red at the bottom and purple at the top.
The color difference occurs because Earth's auroras are dominated by excited nitrogen and oxygen molecules, and Saturn's auroras are dominated by excited hydrogen molecules.
Scientists are still working on additional Cassini data from the aurora as well as the larger picture of how clouds of charged particles move around the planet as it spins and receives blasts of solar material from the sun.
"The auroras at Saturn are some of the planet's most glamorous features – and there was no escaping NASA's paparazzi-like attention”, said Marcia Burton, a Cassini fields and particles scientist at NASA's Jet Propulsion Laboratory, Pasadena, California, who is helping to coordinate these observations.
"As we move into the part of the 11-year solar cycle where the sun is sending out more blobs of plasma, we hope to sort out the differences between the effects of solar activity and the internal dynamics of the Saturn system."
The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. More information about Cassini is available at: http://www.nasa.gov/cassini and: http://saturn.jpl.nasa.gov
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