测量显示出具有结构的热与电浆剖面：温度在约 3,000-4,000 km 高度达峰值，而离子密度在接近 1,000 km 处达峰值，并呈现与天王星偏移且强烈倾斜的磁场几何相关的明显经度变化。Webb 还解析出靠近磁极的两条明亮极光带，以及在带状部分之间的局部耗减区，这表明磁力线过渡效应会影响带电粒子传输；其形态与先前在木星识别出的类似变暗极光区域进行了比较。
一项关键的定量结果是天王星上层大气持续的长期冷却，平均温度约为 426 K（约 150 °C，original value retained），且低于先前地基与太空船时代的估计，延续了自 1990s early 以来观察到的趋势（约 3 decades）。该研究加强了磁层构型控制冰巨行星垂直能量沉积与电离层结构的证据，并改进了对巨行星比较物理以及对类似系外行星大气能量平衡解读的约束。
On 19 February 2026, an international team led by Paola Tiranti (Northumbria University) reported the first 3D vertical mapping of Uranus’s ionosphere using JWST/NIRSpec IFU data, giving a height-resolved view of the upper atmosphere where ionized gas couples to the magnetic field. The observations cover nearly one Uranian rotation from a 15-hour sequence taken on 19 January 2025 (JWST GO program 5073, PI H. Melin), and they target altitudes up to 5,000 km above the cloud tops.
The measurements show a structured thermal and plasma profile: temperatures peak at about 3,000-4,000 km altitude, while ion density peaks near 1,000 km, with clear longitudinal variability tied to Uranus’s offset, strongly tilted magnetic geometry. Webb also resolved two bright auroral bands near magnetic poles plus a localized depletion zone between parts of the bands, indicating magnetic-field-line transition effects on charged-particle transport; the morphology is compared with analogous darkened auroral regions previously identified at Jupiter.
A key quantitative result is continued long-term cooling of Uranus’s upper atmosphere, with an average temperature near 426 K (about 150 °C, original value retained) and lower than earlier ground-based and spacecraft-era estimates, extending a trend observed since the early 1990s (roughly 3 decades). The study strengthens the evidence that magnetospheric configuration controls vertical energy deposition and ionospheric structure on ice giants, improving constraints for comparative giant-planet physics and for interpreting energy balance in analogous exoplanet atmospheres.