What causes Jupiter’s aurora?
This is an image of Jupiter’s aurora, taken by NASA’s Hubble Space Telescope in 1998. Auroras themselves aren’t peculiar to Jupiter; they occur on Earth on both the North and South Poles and are called the aurora borealis and aurora australis, respectively.
Solar winds hitting the atmosphere and centring on the magnetic poles cause the phenomenon on Earth, but on Jupiter it’s caused by the massive gas giant’s own magnetic properties interacting with its upper atmosphere and exciting the gases that exist there, causing them to glow.
What makes this image particularly special is that you can also see the magnetic footprints of three of Jupiter’s four largest moons within the Jovian auroral blue glow. Io, Ganymede and Europa’s own auroras (which are labelled) show up as three blobs of light and the electric currents generated by these three satellites move along the magnetic field of Jupiter while bouncing in and out of the atmosphere.
This shot was taken from the ultraviolet part of the spectrum, so this particular perspective of the aurora cannot be observed with the naked eye. It shows the main oval centred on Jupiter’s magnetic north pole.