As with the aurora borealis on Earth, Saturn’s polar auroras – shot here at the planet’s south pole – are generated by the collision of energetically charged particles into the planet’s upper atmosphere. The difference, however, is that the auroras can streak out to an incredible height of 1,000 kilometres (620 miles) above Saturn’s clouds.
The charged particles are produced primarily by the gas giant’s magnetosphere, though they are also contributed to by the bombardment of solar winds emanating from the Sun. These generated particles impact into the atomic and molecular hydrogen in Saturn’s polar atmosphere, causing the gaseous atoms to ionise. Ultimately this ionisation results in photons being emitted, which combined lead to that distinctive ethereal glow.
Importantly, unlike the auroras we witness here on Earth, those imaged on Saturn are not visible to the human eye. Indeed, the aurora only glows brightly like this at about four micrometres (0.0002 inches), which is six times the wavelength visible to the human eye. The images here were captured by the Cassini space probe’s Visual and Infrared Mapping Spectrometer (VIMS), which can peer deep into the infrared and ultraviolet spectrum.