NASA’s Webb Telescope maps extreme heat on exoplanet WASP-18b, revealing a 5,000°F hotspot and cooler edges.

Astronomers using NASA’s James Webb Space Telescope have created the first 3D temperature map of exoplanet WASP-18b, an ultra-hot Jupiter, by analyzing starlight changes during its eclipse behind its host star. The 3D eclipse mapping technique, applied via JWST’s NIRISS instrument, revealed a central hotspot on the planet’s dayside with temperatures exceeding 5,000°F, where water vapor breaks down, and a cooler ring around its edges. The method, which probes multiple atmospheric layers using infrared wavelengths, marks a major advance in studying exoplanet climates, weather, and chemistry, and is expected to apply to many other hot Jupiters. The findings were published October 28 in Nature Astronomy.