Astronomers are using the NASA/ESA Hubble Space Telescope to study auroras -- stunning light shows in a planet's atmosphere -- on the poles of the largest planet in the Solar System, Jupiter. This observation program is supported by measurements made by NASA's Juno spacecraft, currently on its way to Jupiter. Jupiter's auroras were first discovered by the Voyager 1 spacecraft in 1979. A thin ring of light on Jupiter's nightside looked like a stretched-out version of our own auroras on Earth. Only later on was it discovered that the auroras were best visible using the ultraviolet capabilities of the NASA/ESA Hubble Space Telescope.