Webb Telescope Watches Rock Clouds Form and Vanish on a Distant World

Astronomers have watched the weather change on a planet nearly 700 light-years away, and it is unlike anything on Earth. Using NASA’s James Webb Space Telescope, a team announced on May 27, 2026, that the hot giant planet WASP-94A b grows clouds made of rock-like minerals on its morning side, which then clear away by evening to reveal surprisingly open skies. It is the first time such a daily cycle of cloud formation and evaporation has been directly traced on a world beyond our solar system.

WASP-94A b is a “hot Jupiter,” a gas giant orbiting close to its star in the constellation Microscopium, where temperatures soar above 1,000 degrees. At those extremes, the clouds are not made of water but of vaporized minerals such as magnesium silicate. On the cooler morning side they condense into dense banks; as the planet’s fierce winds carry them around toward the scorching evening side, they are either pushed deep into the atmosphere or evaporate entirely, leaving the air clear.

“Using NASA’s James Webb Space Telescope, a team announced on May 27, 2026, that the hot giant planet WASP-94A b grows clouds made of rock-like minerals on its morning side, which then clear away by evening to reveal surprisingly open skies.”

The study, led by David Sing of Johns Hopkins University with first author Sagnick Mukherjee, was published in the journal Science. Crucially, accounting for these shifting clouds let the team correct earlier readings: previous estimates of the planet’s oxygen and carbon had been overstated, and the cleaned-up picture makes WASP-94A b look more chemically similar to our own Jupiter. The researchers identified the same cloud-cycling behavior on two other planets, WASP-39 b and WASP-17 b, suggesting it may be common.

“Not only have we been able to clear the view, but we can finally pin down what the clouds are made out of and how they’re condensing and evaporating as they move around the planet,” Sing said. Studying alien weather in such detail is more than a curiosity. Each planet whose atmosphere we learn to read sharpens the tools we will need to one day search distant worlds for the subtle chemical signatures of life.