Hubble Spots Giant Blue Auroras Over Saturn's North Pole

A gorgeous animation released today by the European Space Agency (ESA) unveils stunning blue auroras dancing over Saturn's north pole.

Based on a series of observations taken with the Hubble Space Telescope in 2017, the animation shows Saturn's "fluttering auroras" glowing blue as the planet spins around on its axis.

According to the space agency, the auroras on Saturn are quite different from those seen on Earth, and only shine in ultraviolet light — a part of the electromagnetic spectrum blocked by our planet's atmosphere and which can only be studied from space.

The reason why Saturn's auroras are only visible to space telescopes and can be detected solely in the ultraviolet spectrum has to do with the composition of the gas giant's atmosphere. Similar to Jupiter, Uranus, and Neptune — which also boast splendid auroras, notes the Hubble Space Telescope website — Saturn's atmosphere is "dominated by hydrogen," which gives off ultraviolet light, explains ESA.

This means that, although Saturn's northern auroras are imaged here in blue, their cerulean glow is actually attributed to ultraviolet light, notes Gizmodo.

In contrast, terrestrial blue auroras are created when solar winds — an outflow of charged particles coming from the sun — seep into our planet's magnetosphere (the region of space around a planet where charged particles interact with its magnetic field) and meet nitrogen atoms, the Inquisitr previously reported.

In fact, the animation (seen above) was created from a composite image (shown at the beginning of this article) released on the same day, stitched together from two different types of Hubble observations, revealed ESA.

On one hand, the photo contains last year's ultraviolet observations, taken over a period of seven months and coordinated with the final act of the historic Cassini mission — dubbed the "Grand Finale", which lasted from April 26, 2017, until the space probe's controlled crash into Saturn on September 15, 2017, as reported by the Inquisitr.

On the other hand, the composite image contains a more recent view of Saturn, captured by Hubble in visible light sometime in early 2018 and superimposed on the 2017 ultraviolet observations.

Blue auroras over Saturn's north pole.
ESA/Hubble, NASA, A. Simon (GSFC) and the OPAL Team, J. DePasquale (STScI), L. Lamy (Observatoire de Paris)
Ultraviolet image of the spectacular auroras sighted over Saturn's north pole.

Taken with Hubble's STIS instrument (short for Space Telescope Imaging Spectrograph), the ultraviolet observations were captured before and after the Saturnian northern summer solstice, and represent "the most comprehensive picture so far of Saturn's northern aurora," stated ESA officials.

Both the composite and the ultraviolet image of Saturn's northern auroras depict "a rich variety of emissions with highly variable localized features," as seen in the video below.

A close-up of Saturn's auroras, the short clip reveals how the planet's northern light show evolved during the observation period under the influence of the solar wind and the rapid rotation of Saturn, which spins twice as fast as Earth and completes a full rotation in about 11 hours. By comparison, our planet rotates once every 23.934 hours, which means that a day on Saturn is twice as short as a day on Earth.

"On top of this, the northern aurora displays two distinct peaks in brightness — at dawn and just before midnight. The latter peak, unreported before, seems specific to the interaction of the solar wind with the magnetosphere at Saturn's solstice," ESA detailed in the photo release.