Astronomers have produced the first-ever three-dimensional map of a planet exterior our photo voltaic system — WASP-18b — marking a significant leap ahead in exoplanet analysis.
Using the James Webb Space Telescope, researchers utilized a brand new approach known as 3D eclipse mapping, or spectroscopic eclipse mapping, to trace delicate modifications in varied mild wavelengths as WASP-18b moved behind its star. These variations allowed scientists to reconstruct temperature throughout latitudes, longitudes and altitudes, revealing distinct temperature zones all through the planet’s ambiance.
“If you build a map at a wavelength that water absorbs, you’ll see the water deck in the atmosphere, whereas a wavelength that water does not absorb will probe deeper,” Ryan Challener, a postdoctoral associate in Cornell’s Department of Astronomy and lead author of a study published on the research, said in a statement. “If you put those together, you can get a 3D map of the temperatures in this atmosphere.”
WASP-18b is positioned about 400 light-years from Earth; it has roughly 10 occasions Jupiter’s mass and completes an orbit of its host star in simply 23 hours. Because it is so near its star, temperatures within the planet’s ambiance attain almost 5,000 levels Fahrenheit (2,760 levels Celsius). Those scorching circumstances made it a super candidate for testing the brand new technique of 3D temperature mapping.
The map revealed a brilliant central hotspot surrounded by a cooler ring on the planet’s dayside — it has a tidally locked orbit, which means that one facet of the planet is at all times dealing with its star — demonstrating that the exoplanet’s winds fail to distribute warmth evenly throughout the ambiance.
Remarkably, the hotspot confirmed decrease water vapor ranges than WASP-18b’s atmospheric common. “We think that’s evidence that the planet is so hot in this region that it’s starting to break down the water,” Challener stated. “That had been predicted by theory, but it’s really exciting to actually see this with real observations.”
This new 3D eclipse mapping approach will open many doorways in exoplanet observations, because it “allows us to image exoplanets that we can’t see directly, because their host stars are too bright,” stated Challener. As 3D eclipse mapping is utilized to different exoplanets noticed by Webb, “[w]e can start to understand exoplanets in 3D as a population, which is very exciting,” he added.
The group’s analysis was printed within the journal Nature Astronomy on October 28, 2025.