Earth isn't the only planet to showcase spellbinding northern or southern Lights, otherwise called auroras. Now for the first time, NASA has caught an unprecedented 360-degree view of Saturn's own dancing light show at its poles.
The magnificent spectacle was captured thanks to a combined effort by the Hubble Space Telescope, orbiting around Earth, and NASA's Cassini spacecraft, orbiting around Saturn. While the Hubble telescope observed Saturn's northern auroras in ultraviolet wavelengths, Cassini got complementary close-up views in infrared, visible-light and ultraviolet wavelengths. Cassini's close-up view also allowed it to capture parts of the planet's northern and southern auroras that don't face the Earth, providing a perspective on this light show like no other to date.
"This is our best look yet at the rapidly changing patterns of [Saturn's] auroral emission," said Wayne Pryor, a Cassini co-investigator at Central Arizona College in Coolidge, Ariz. "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."
The detailed images were so intricate that they allowed researchers to tie the changes in the auroras to the fluctuating wind of charged particles blowing off the sun and flowing past Saturn. They also make it possible to analyze how Saturn's intricate magnetic dance with its moons influences the behavior of the auroras.
The visible-light views might the be most awe-inspiring images from the project, however. They reveal for the first time exactly what the colors of Saturn's auroras would be to the naked eye. Unlike Earth's auroras, which dazzle like green and red curtains flowing in the wind, Saturn's auroras are primarily purple and red in color. The variance is due to the two planets' different atmospheres.
"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," said Ulyana Dyudina, a scientist at Caltech's Division of Geological and Planetary Sciences. "We were thrilled to learn about this colorful display that no one had seen before."
The work is already revolutionizing how researchers study and understand the atmospheres and magnetic fields at play in other planets. Previous ground-based observations were limited by the unavoidable disturbances coming from Earth's atmosphere. But Hubble and Cassini now allow researchers to remove this gauze, and to view alien worlds at angles unseen before.
"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," said Marcia Burton, a Cassini fields and particles scientist at NASA's Jet Propulsion Laboratory.
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