Jupiter's X-ray aurora
Andrew Smith, a PhD student in the Space Environment Physics group working on Saturn and Mercury's magnetotails, tells us of a new development in research into Jupiter's aurora….
At Earth, about 100km above us, the atmosphere is mostly oxygen, and the aurora emits light in the visible region of the electromagnetic (EM) spectrum (mainly as red and green light). At Jupiter and Saturn, the atmospheres are mostly hydrogen and helium, which means the auroral light they emit is mainly ultraviolet light (in between purple light and X-rays). However, UV light and X-rays are next to each other in the EM spectrum, and Jupiter also emits some X-rays from its auroral regions.
Previously, teams using space based telescopes (such as NASA's Chandra and ESA's XMM-Newton) had located an X-ray hot spot near Jupiter’s north pole. This hot spot has been seen to pulse with gaps of between 10 and 45 minutes, or not at all. Recently, a team led by William Dunn in the Planetary Atmospheres & Exoplanets research group at UCL found a southern counterpart to the northern hot spot. Weirdly, this hot spot pulses at different times than the northern one!