Quoting from Nat.Geo. article (which has that same UV image),
Then, in 2010 and 2011, Hubble took a close look at the moon. More
specifically, it looked at the auroral bands ringing Ganymede’s poles.
Hubble studied the auroras in the ultraviolet, but Saur said the
shimmering lights would be visible to human eyes.
“If somebody could be standing ...