Overview
- The peer-reviewed study, led by Paola Tiranti and published February 19 in Geophysical Research Letters, presents the first three-dimensional map of an ice giant’s ionosphere.
- JWST observed Uranus for about 15 hours in January 2025 under General Observer program 5073, using the NIRSpec Integral Field Unit to capture faint H3+ emissions.
- Two bright auroral bands appear near the magnetic poles with a distinct depletion zone between them, a pattern linked to Uranus’s highly tilted and offset magnetic field.
- Vertical profiling shows ion temperatures peaking roughly 3,000–4,000 kilometers above the cloud tops while ion densities peak near 1,000 kilometers, with emissions traced up to ~5,000 kilometers.
- Measurements report an average upper-atmosphere temperature near 426 kelvins (about 150°C), extending a multi-decade cooling trend and refining energy-balance models for ice giants and similar exoplanets.