Saturn's collapsing magnetic tail behind auroras on the planet

Researchers have captured stunning images of Saturn's auroras as the planet's magnetic field is battered by charged particles from the Sun.

The team's findings provide a "smoking gun" for the theory that Saturn's auroral displays are often caused by the dramatic collapse of its "magnetic tail."

Just like comets, planets such as Saturn and the Earth have a "tail"-known as the magnetotail - that is made up of electrified gas from the Sun and flows out in the planet's wake.

When a particularly strong burst of particles from the Sun hits Saturn, it can cause the magnetotail to collapse, with the ensuing disturbance of the planet's magnetic field resulting in spectacular auroral displays. A similar process happens on Earth too.

Scientists observed this process happening on Saturn firsthand between April and May of 2013 as part of a three-year-long Hubble observing campaign.

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 out from the Sun.

Due to the composition of Saturn's atmosphere, its auroras shine brightly in the ultraviolet range of the electromagnetic spectrum. This observation campaign using Hubble meant the astronomers were able to gather an unprecedented record of the planet's auroral activity.

The team caught Saturn during a very dynamic light show. Some of the bursts of light seen shooting around Saturn's polar regions travelled at over three times faster than the speed of the gas giant's rotation.

The findings are set to be published in Geophysical Research Letters, a journal of the America Geophysical Union.