Auroras on Saturn

Astronomers using the NASA/ESA Hubble Space Telescope have captured new images of the dancing auroral lights at Saturn’s north pole. Taken in April and May 2013 from Hubble’s perspective in orbit around Earth, these observations provide a detailed look at previously unseen dynamics in the choreography of the auroral glow.

The ultraviolet images, taken by Hubble’s super-sensitive Advanced Camera for Surveys, capture moments when Saturn’s magnetic field is affected by bursts of particles streaming from the Sun.

Saturn’s magnetosphere – the vast magnetic ‘bubble’ that surrounds the planet – is compressed on the Sunward side of the planet, and streams out into a long ‘magnetotail’ on the nightside.

It appears that when particles from the Sun hit Saturn, the magnetotail collapses and later reconfigures itself, an event that is reflected in the dynamics of its auroras.

Saturn was caught during a very dynamic light show – some of the bursts of light seen shooting around Saturn’s polar regions traveled more than three times faster than the speed of the gas giant’s roughly 10-hour rotation period!

The new observations were taken as part of a three-year Hubble observing campaign, and are presented in a paper published in the journal Geophysical Research Letters. The images complement those taken by the international Cassini spacecraft orbiting Saturn.

Image credit: NASA/ESA, Acknowledgement: J. Nichols (University of Leicester)

Saturn's Auroras

Ultraviolet and infrared images from NASA's Cassini spacecraft and Hubble Space Telescope show active and quiet auroras at Saturn's north and south poles.

Saturn's auroras glow when energetic electrons dive into the planet's atmosphere and collide with hydrogen molecules. Sometimes a blast of fast solar wind, composed of mostly electrons and protons, creates an active aurora at Saturn, as occurred on April 5 and May 20, 2013.

The first set of images, as seen in the ultraviolet part of the spectrum by Hubble, shows an active aurora dancing around Saturn's north pole on April 5. The movie then shows a relatively quiet time between April 19 to 22 and between May 18 and 19. The aurora flares up again in Hubble images from May 20. This version, shown in false-color, has been processed to show the auroras more clearly.

A second set of ultraviolet images shows a closer view of an active north polar aurora in white. This set comes from Cassini ultraviolet imaging spectrograph observations on May 20 and 21.

The last set of images, in the infrared, shows a quiet southern aurora (in green) in observations from Cassini's visual and infrared mapping spectrometer on May 17. Saturn's inner heat glows in red, with dark areas showing where high clouds block the heat.

Video credit: NASA/JPL-Caltech/University of Colorado/Central Arizona College and NASA/ESA/University of Leicester and NASA/JPL-Caltech/University of Arizona/Lancaster University

Note: For more information, see PIA17668: Saturn's Colorful Aurora, NASA Spacecraft Get a 360-Degree View of Saturn's Auroras and PIA17669: Pulses from the Sun.

Titan's North Polar Collar

Titan's polar collar -- previously seen by Voyager 2 and the Hubble Space Telescope -- has now been observed by the Cassini spacecraft, seen here in ultraviolet light. The collar is believed to be seasonal in nature. Researchers are still studying its cause and evolution.

This view looks toward the Saturn-facing hemisphere of Titan. North on Titan is up and rotated 32 degrees to the right. The image was taken with the Cassini spacecraft narrow-angle camera on April 13, 2013 using a spectral filter sensitive to wavelengths of ultraviolet light centered at 338 nanometers.

The view was acquired at a distance of approximately 1.1 million miles (1.8 million kilometers) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 4 degrees. Image scale is 7 miles (11 kilometers) per pixel.

Photo credit: NASA/JPL-Caltech/Space Science Institute