The last time we got an up close and personal look at Uranus was in 1986, when Voyager 2 flew past and did some probing. Back then, we got some spectral hints that Uranus had aurorae, but it's taken another 25 years for Hubble to take some pictures of the light show in action.
Just like Earth, Uranus has a magnetic field that extends out into space. Since Uranus rotates nearly completely sideways, though, that field has some peculiar properties that we don't entirely understand. Earth's magnetic field interacts with the solar wind from the sun to generate auroras at high latitudes, and while the same sort of thing happens on Uranus, the sideways magnetic field means that the Uranus aurorae are a bit weird: they're very small, they're not where we'd expect them to be and they only last a few minutes at a time.
As Uranus travels around the sun, it's relative orientation has been changing for the last few decades, and it's recently become possible for us to get a much better view of its poles. Over the last year, astronomers waited for large solar flares pointed towards Uranus, and then scheduled observation time on Hubble too see what effect the mass of charged particles had on the planet. The space telescope was able to snap the pictures of active aurorae shown above.
The hope here is that understanding the magnetosphere of strange planets like Uranus might help us understand how our own magnetosphere works, potentially leading to better ways of protecting us from solar flares and/or creating superheroes.