A spectacular display of northern lights on Saturn has been captured by the Hubble telescope for over half a year in 2017.
Auroras are a common phenomenon that appears when high energy particles found in sunrays collide with the magnetic shield that protects the Earth, and with gas molecules such as oxygen, resulting in an incredible view as green, red and violet lights fill the sky. They are encountered at the North and South Pole. Northern lights fascinated humanity for centuries as they struggled to understand how they appear. The first link between their occurrence and solar activity was theorized in 1880. It would take several decades in order to identify all the participants. While the Poles are the best location to observe them, they can also be seen in many countries around the world, in both the northern and southern hemisphere. Ideally, they should be locations with little no to light pollution. On Earth, they can be observed all year long, with a peak activity period every 11 years.
The occurrence of auroras has been observed on other planets from our solar system, namely the giant planets Neptune, Jupiter, and Uranus. On Earth they can be freely admired since our atmosphere is clear. On gas planets like Saturn, the situation is a little bit different. Since the atmosphere is extremely rich in hydrogen, most of the auroras appear as ultraviolet light.
In order to capture the elusive northern lights, Hubble used its built-in STIS (Space Telescope Imaging Spectrograph) over several months before apex periods during the summer solstice. Impressive pictures were captured, with scientists noting the auroras during the solstice were the brightest auroras observed on Saturn until now. A combination between peak solar winds and the fact that Saturn has an accelerated rotation may have contributed to the magnitude of the phenomenon.
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