February 11, 2014
NASA Spacecraft Capture Stunning Views Of Saturn’s Dancing Auroras
[ Watch the Video: Saturn Puts On Quite A Light Show ]
Lee Rannals for redOrbit.com - Your Universe Online
Two NASA spacecraft captured 360 degree views of Saturn’s northern lights, giving a glimpse as to how the ringed planet looks when bathed in the Sun’s charged particles.
Using the Hubble Space Telescope and Cassini, NASA collaborated along with international researchers to put together the footage of the Saturnian show. Hubble provided an ultraviolet wavelength view of the auroras, while Cassini gave scientists the close-up views in infrared and visible-light.
“The result is a kind of 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,” NASA said in a statement.
Auroras are the result of solar flares, causing collisions of energetic charged particles with atoms in the high latitude atmosphere. The charge particles sent off by the solar wind are directed into a planet’s magnetic field and into the atmosphere, creating the “dancing lights” effect.
"Saturn's auroras can be fickle -- you may see fireworks, you may see nothing," Jonathan Nichols, of the University of Leicester in England, who led the work on the Hubble images, said in a statement. "In 2013, we were treated to a veritable smorgasbord of dancing auroras, from steadily shining rings to super-fast bursts of light shooting across the pole.”
[ Watch the Video: Dance of Saturn's Auroras ]
The Cassini images feature a look at the changing patterns of faint emissions of scales of a few hundred miles. These changes in the aurora are tied to the fluctuating wind of charged particles blowing off the sun and blowing past Saturn.
"This is our best look yet at the rapidly changing patterns of auroral emission," Wayne Pryor, a Cassini co-investigator at Central Arizona College in Coolidge, Ariz, said in a statement. "Some bright spots come and go from image to image. Other bright features persist and rotate around the pole, but at a rate slower than Saturn's rotation."
Researchers will be able to use this data to answer some long-standing questions about the atmospheres of giant outer planets. Scientists have questioned why the high atmospheres of gas giants are heated beyond what might normally be expected due to their vast distances from the sun.
"By looking at these long sequences of images taken by different instruments, we can discover where the aurora heats the atmosphere as the particles dive into it and how long the cooking occurs,” Sarah Badman, a Cassini visual and infrared mapping spectrometer team associate at Lancaster University, England, said in a statement.
Scientists can use the visible-light data to figure out the colors of Saturn’s auroras, which show red and purple. On Earth, auroras mostly shine green with some red at the top. According to NASA, these color differences are due to the different molecules in both planets. Earth’s auroras are created by excited nitrogen and oxygen molecules, while Saturn’s auroras derive from hydrogen molecules.
"While we expected to see some red in Saturn's aurora because hydrogen emits some red light when it gets excited, we also knew there could be color variations depending on the energies of the charged particles bombarding the atmosphere and the density of the atmosphere," Ulyana Dyudina, an imaging team associate at the California Institute of Technology, Pasadena, Calif, said in a statement. "We were thrilled to learn about this colorful display that no one had seen before."
These images will help scientists learn more about how clouds of charged particles move around the planet as it spins and comes into contact with solar material.
"The auroras at Saturn are some of the planet's most glamorous features – and there was no escaping NASA's paparazzi-like attention”, Marcia Burton, a Cassini fields and particles scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif, said in a statement. "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."
Image Caption: While the curtain-like auroras we see at Earth are green at the bottom and red at the top, NASA's Cassini spacecraft has shown us similar curtain-like auroras at Saturn that are red at the bottom and purple at the top. Credit: NASA/JPL-Caltech/SSI