Science Daily offered a lot of JWST Tuesday. Today this blog checks in on the HAT-P-18 system. A Saturn transits this one, close-in. But also starspots transit this one's surface.
JWST can tease them apart, from 500 lightyears. This allows sharper definition on the planet's shape. They used to think the planet was hazy; now, deleting the noise from starspots, there's less of that haze. There's a better-defined cloud deck instead - much like Saturn over here.
That further means there's a tenth the water than they'd originally thought; and none of the methane. At nearly 500 K over 10 kPa boiling-point (which is 373 K) it's hard to see where a Saturnlike would hold water. As to what's in the clouds, that could still be the water; Venus has clouds and almost no water; those clouds' hydroxides are locked in acid and sulfates.
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