The cosmos is full of objects that lacked the mass to become stars. These 'failed stars'—brown dwarfs — resemble campfire embers that never ignited, just slowly smoldering and cooling. The James Webb Space Telescope peered at the coldest of them, whose heat is comparable to a hot frying pan, and split their light into its components (a technique called spectroscopy). After studying 22 objects of varying temperatures, scientists noticed a pattern: hotter dwarfs are transparent, while the coldest ones appear to hang gray clouds, like smoke over dying embers.
As they cool, the air gradually gains more water vapor, methane, and ammonia. But the most unexpected twist: even in these cold worlds, where eternal stillness was assumed to reign, chemical storms are raging — with mists, tempests, and possibly rains of molten metal.
The excess of carbon monoxide in WISEPAJ1541-22 came as a surprise: in such cold conditions, it should vanish quickly. So the atmosphere must be constantly 'churned up' by powerful storms.