Uranus time-lapse rotation (January 2025, annotated)

This timelapse video is believed to be the only dataset to date that has continuously observed a full rotation of Uranus by a single telescope, which was facilitated by Webb’s uniquely positioned orbit at L2 that observed the planet for approximately 17 hours. This time-lapse video consists of over 1200 slices of multi-object spectroscopy data. By mapping distribution and temperature of trihydrogen cation and molecular hydrogen, these observations provide the most detailed view to date of Uranus’ vertical upper atmosphere. The video shows where temperatures and ion densities peak, and reveals clear auroral structures shaped by the planet’s unusual magnetic field.

An international team of astronomers have now uncovered how temperature and charged particles vary with height across the planet. Using Webb’s NIRSpec instrument, the team detected the faint glow from molecules high above the clouds. These unique data provide the most detailed portrait yet of where the planet’s auroras form, how they are influenced by its unusually tilted magnetic field, and how Uranus’s atmosphere has continued to cool over the past three decades. The results offer a new window into how ice-giant planets distribute energy in their upper layers.