Astronomers using NASA’s Chandra X-ray Observatory have detected X-ray emissions from the ice giant Uranus for the first time in a new analysis of imagery collected in 2002 and again in 2017 when a possible flare was observed. As with X-ray emissions seen at Jupiter and Saturn, the researchers conclude most of the high-energy radiation detected at Uranus is caused by sunlight scattering from the planet’s atmosphere. But there are hints that at least one other source may be present. One possibility is that the rings of Uranus produce X-rays through interactions with charged particles in the nearby environment. Another possibility is X-rays produced in auroras on Uranus, a phenomenon observed at other wavelengths. X-rays from Uranus are particularly interesting because the planet’s rotation axis is tilted nearly parallel with its path around the Sun while its magnetic field is tilted by a different amount and offset from the planet’s center. This may result in complex and variable auroras. Ongoing analysis of X-ray emissions could shed new light on these processes.
Using a new process in planetary formation modelling, where planets grow from tiny bodies called “pebbles,” Southwest Research Institute scientists can explain why Mars is so much smaller than Earth. This same process also explains the rapid formation of the gas giants Jupiter and Saturn, as reported earlier this year.