Astronomers using NASA's James Webb Space Telescope discovered an exoplanet that develops thick mineral clouds every morning which vanish by nightfall [1].
This discovery provides a rare glimpse into the volatile atmospheric chemistry of distant worlds. By observing how clouds form and dissipate in a single day, scientists can better understand the thermal dynamics and composition of planets outside our solar system.
The planet, known as WASP-94A b, is located approximately 700 light-years from Earth [1]. Data collected this month indicates that the planet undergoes a dramatic daily weather cycle. Mineral vapors in the atmosphere condense into rock-like clouds during the cooler morning hours [3]. As temperatures rise toward the evening, these clouds evaporate or settle, leaving the night sky clear [2].
These findings were reported in several scientific updates throughout May 2026 [1, 4]. The process is driven by the extreme temperature swings on the planet. Because the mineral vapors are sensitive to heat, they only maintain a cloud-like state during the brief window of relative coolness [3].
The James Webb Space Telescope's ability to detect these specific atmospheric changes allows researchers to map the transition between the day and night sides of the planet. This level of detail was previously unattainable for worlds so far from the solar system [2]. The observations confirm that the "rock clouds" are not permanent fixtures but are transient features of the planet's environment [3].
“WASP-94A b develops thick mineral clouds each morning that disappear by nightfall”
The detection of a daily cloud cycle on WASP-94A b demonstrates the precision of the James Webb Space Telescope in monitoring atmospheric evolution in real-time. This suggests that other high-temperature exoplanets may have similarly dynamic weather patterns, where minerals, rather than water, drive the climate, fundamentally changing how astronomers model planetary atmospheres.
