Image Credit: ESA/Webb, NASA, CSA, STScI, P. Tiranti, H. Melin, M. Zamani (ESA/Webb).
Planet Uranus is one of the least studied worlds in our own Solar System. Only one probe has ever done a flyby of Uranus - NASA’s Voyager 2 in 1986. That fleeting visit was our only detailed snapshot of the planet, leaving us unaware of its fundamental properties and environment. In reality, Uranus is anything but boring. Its lopsided axial tilt and rotation hint at a very chaotic history, and the new images, which include our first view of the Uranus’s glowing auroras, reveal just that.
A magnificent timelapse of Uranus as it completes a full rotation, revealing the glowing auroras near its bright pole (Image Credit: ESA/Webb, NASA, CSA, STScI, P. Tiranti, H. Melin, M. Zamani (ESA/Webb)).
Despite its oddities, Uranus actually reveals to us some of the most common properties scientists think planets in our universe have. Worlds with similar sizes and masses to Uranus and Neptune are some of the most common in the cosmos, and they give us critical information about the nature of exoplanets. Understanding how Uranus formed and evolved would in turn tell us how billions of worlds across our Milky Way galaxy also developed.
Image Credit: ESA/Webb, NASA, CSA, STScI, P. Tiranti, H. Melin, M. Zamani (ESA/Webb).
This is where the James Webb Space Telescope has become so helpful. By looking at Uranus as it rotates around its pole, astronomers can map its entire upper atmosphere in higher detail than ever before, following the paths of charged particles to thousands of kilometers above the ice giant’s clouds. This is the first time scientists have been able to reconstruct a 3D view of the planet’s ionosphere, which is the area that the auroras form. These observations are helping astronomers figure out how temperature and the density of particles changes in different layers of the atmosphere.
The previous image of the Uranus system captured by JWST. While it shows impressive clarity, the auroras are not visible, as the telescope was not tuned into the correct wavelength of light (Image Credit: NASA, ESA, CSA, Maryame El Moutamid (SwRI), Matthew Hedman (University of Idaho); Image Processing: Joseph DePasquale (STScI)).
The results have also confirmed a long-standing mystery: the upper atmosphere of Uranus seems to be cooling, reaching temperatures lower than any of the ones recorded by previous spacecraft or telescopes. The Webb data obtained also offers us the clearest view of another planet’s internal structure that would usually only be doable with a dedicated mission.