SMRTR Science & EngineeringMay 21, 2026Ars Technica

JWST maps the weather on a hot gas giant 700 light-years away

SMRTR summary

Cloudy mornings, clear evenings. It sounds like a routine weather forecast, but this is the weather report for a planet 690 light-years away.

Using the James Webb Space Telescope, scientists at Johns Hopkins University studied WASP-94A b, a gas giant so close to its star that one side permanently bakes in daylight while the other freezes in eternal night. By splitting the planet's light signal during transit, they captured separate atmospheric readings for its morning and evening sides, finding thick clouds on one, clear skies on the other.

The twist? When researchers analyzed the atmosphere the old way, averaging everything together, their chemical estimates went wildly off, overstating the planet's oxygen enrichment by a factor of roughly 20.

"This had a huge effect on our understanding of the composition of this planet," says astrophysicist Sagnick Mukherjee.

The implications are unsettling for exoplanet science broadly, suggesting our chemical portraits of distant worlds may be far less accurate than we thought.

SMRTR provides this summary for quick context. The original article belongs to Ars Technica.

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