Webb Finds 700-Light-Year Exoplanet With Daily Rock Clouds That Vanish by Night
Updated
Updated · ScienceDaily · May 29
Webb Finds 700-Light-Year Exoplanet With Daily Rock Clouds That Vanish by Night
7 articles · Updated · ScienceDaily · May 29
WASP-94A b, a giant planet nearly 700 light-years away, shows magnesium-silicate clouds on its morning side that are largely gone by evening, one of the first direct observations of cloud cycling on a hot Jupiter.
JWST detected the split by separately probing the planet's leading and trailing edges during transit, revealing cooler, cloudier mornings and clearer evenings on the side rotating back toward darkness.
Temperatures above 1,000 degrees on the day side may either evaporate the mineral clouds or drive them deeper into the atmosphere, producing the stark day-night contrast.
Clearer evening skies let researchers isolate the atmosphere itself, revising estimates of oxygen and carbon to about 5 times Jupiter's levels rather than the hundreds of times suggested by earlier data.
The team has already spotted similar cloud cycling on 2 more hot Jupiters—WASP-39 b and WASP-17 b—and plans a broader JWST survey of exoplanet weather.
With skies of vaporized rock now found, what even more extreme alien weather will Webb discover next?
If rock clouds hid giant planets’ true nature, what other cosmic secrets are we currently misinterpreting?
Breakthrough in Exoplanet Meteorology: JWST Detects Daily Cloud Cycles on Hot Jupiters
Overview
In May 2026, scientists using the James Webb Space Telescope made the first-ever discovery of daily cloud cycles on exoplanets, starting with the hot Jupiter WASP-94A b. For years, thick clouds had blocked detailed views of these distant worlds, but new JWST observations cleared this fog, allowing researchers to finally see what the clouds are made of and how they change throughout the day. This breakthrough not only reveals the dynamic weather on exoplanets but also marks a major step forward in understanding their atmospheres and the processes shaping them.