Saturn’s auroras pulled by the tail
Saturn’s auroras are caused by the collapse of the magnetotail, stressed by bursts of solar wind. This is the result of a new study led by the University of Leicester and based on images taken by the Hubble Space Telescope in 2013
Scientists first observed Saturn’s auroras in 1979. Decades later, these iridescent ribbons of light still captivate. On one side, they are marvelously tall, expanding hundreds of miles directly above the planet’s poles. Torrents of charged particles flaming from the Sun collide with Saturn’s magnetic field, generating an aurora on the planet’s South Pole. The Saturn’s auroras can last for days, unlike the short-lived ones of our planet. Scientists combined ultraviolet images of the auroras, taken by Hubble over a period of days, with visible-light images of the ringed planet. 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. In this view the aurora appears blue because of the ultraviolet camera, but a Saturn-based observer would see red light flashes.
The Hubble and Cassini images were focused on April and May of 2013. 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 weak emissions on scales of a few hundred kilometers and tied the changes in the auroras to the fluctuating wind of charged particles blowing off the Sun and flowing past Saturn.
Many scientific studies have been dedicated to decipher the movements of a distant choreography. A study based on their observations between April and May 2013 was orchestrated by Jonathan Nichols, Department of Physics and Astronomy, University of Leicester, and now being published in the journal Geophysical Research Letters.
Just as the Earth, Saturn has a magnetic “tail”, an area where the planet’s magnetic field extends under the influence of the solar wind. Scientists have long suspected that it is the collapse of the magnetotail due to the intense auroral activity on Saturn, in a manner very similar to what is happening on our planet. The authors of the new study believe they have found, thanks to the Hubble images, the most convincing evidence to date of the validity of this theory.
Scientists have captured amazing shots of auroras moving quickly around the north pole of the planet. The phenomenon happened at the time when the magnetic tail was saturated with particularly intense flows of ionized particles from the sun which caused the stretching and collapse. This induced massive disturbance to the magnetic field.
“Our observations show a flare up of auroras move very fast around the polar region of the planet. We can see that the magnetotail is under great turmoil and constantly reconfiguring, under the influence of the solar wind”, said Nichols. “And the smoking gun we were looking for shows that the magnetotail is collapsing.”