EnviroTREC has written and reproduced several stories about northern lights on our webpages. Here is a story about “northern lights” on Saturn!

This image is a composite of observations made of Saturn in early 2018 of the auroras on the planet’s north pole region, made in 2017. In contrast to the auroras on Earth, the auroras on Saturn are only visible in the ultraviolet — part of the electromagnetic spectrum blocked by Earth’s atmosphere. Therefore, astronomers have to rely on space telescopes like the NASA/ESA Hubble Space Telescope to study them. (ESA/Hubble, NASA, A. Simon (GSFC)

The gas planet’s aurora was seen dancing across its north pole

Originally written by Nicole Mortillaro for CBC News on August 31st 2018

Over a period of seven months in 2017, the Hubble Space Telescope photographed a beautiful display of northern lights over Saturn’s north pole.

Here on Earth, people experience the northern lights (southern lights in the southern hemisphere) when fast-moving particles from the sun travel along the solar wind and interact with the planet’s magnetic field.

Auroras, also called the northern or southern lights, are caused by charged particles moving down toward the poles and then interacting with molecules of nitrogen and oxygen which transform the sky into bright bands of green, red and violet lights.

Earth is not the only planet to experience this spectacular phenomenon. The giant outer planets — Jupiter, Saturn, Uranus and Neptune — also get northern and southern lights.

Here on Earth, people can look up and appreciate the colourful display, but it’s a little different with planets like Saturn which are mostly made of gas. Because these planets contain mostly hydrogen, the displays can be seen mainly in ultraviolet light.

To capture the northern lights, Hubble used its Space Telescope Imaging Spectrograph over the months before and after Saturn’s northern summer solstice, when the poles are tilted toward the sun.

The image, observed with the Space Telescope Imaging Spectrograph in the ultraviolet, shows the auroras surrounding Saturn’s north pole region. The variability of the auroras is influenced by solar winds and the rapid rotation of Saturn. (ESA/Hubble, NASA & L. Lamy Obse)

Though Saturn’s auroras have been photographed before by Hubble, these new images reveal the auroras peaking in brightness around dawn and just before midnight.

This had never been observed before. Scientists believe the phenomenon has something to do with solar winds interacting with the planet’s magnetosphere during the solstice, as well as the speed at which Saturn rotates, roughly once every 11 hours.

While Earth’s auroras stretch upward around 100 to 500 km into the atmosphere, Saturn’s auroras can reach heights of more than 1,200 km.

Seemingly, the conditions that create northern lights on Saturn: gases in the upper atmosphere and a planetary magnetic field!