Some 158 light-years away, around the dim star TOI-6894, a red dwarf, a planet moves leisurely. Its year lasts less than two Earth days, yet it is a cool world with an equilibrium temperature around 420 K, just a bit warmer than a sauna. This exoplanetary giant, TOI-6894 b, almost exactly mirrors Saturn's size, though it weighs noticeably less. Its star is one of the calmest in its class, free of violent flares and dark starspots that usually blind telescopes. This very calmness allowed JWST to capture, for the first time, a clean, almost laboratory-grade spectrum of the atmosphere of a planet of this type.

Imagine a cosmic kitchen: the star is the stove where planets are cooked; the protoplanetary disk is the pantry with ingredients; and the planet itself is the finished dish. Astronomers suspected that the recipes for gas giants change depending on how hot the 'stove' is. But TOI-6894 b upends this notion. Its atmosphere is the finished dish, and spectroscopy let us taste it.

The spectrum, taken by the NIRSpec instrument in PRISM mode, revealed a full suite of volatile molecules. Water filled the plateau between 2.5 and 3.0 µm, methane etched characteristic dips at 1.6–1.7 and 2.2–2.4 µm, and carbon dioxide produced a strong peak near 4.3 µm. But the biggest surprise was carbon disulfide (CS₂)—a molecule born of photochemistry: the star's ultraviolet light, albeit weak, triggers reactions that turn some carbon and sulfur into this pungent substance (on Earth, it smells like rotting apples). Its peak at 4.65 µm dominates the long-wavelength end of the spectrum.

Models indicate a metallicity 3–10 times higher than solar. But here's the key: the C/O, N/O, and S/O ratios turned out to be practically the same as those of our Sun, and consequently, of Jupiter and Saturn. The ingredients are the same, the proportions are the same, even though the 'stove'—a low-mass red dwarf — is five times lighter than the Sun and cannot heat the surroundings as vigorously. This is a strong argument that core accretion is a universal mechanism, operating even in sparse protoplanetary disks. The planet managed to gather about 12 Earth masses of heavy elements, then rapidly accrete a gaseous envelope. Gravitational instability, another possible scenario, could not so neatly reproduce solar proportions. It seems the universe's cookbook is uniform, and our Jupiter and Saturn are not unique masterpieces but typical dishes from the galactic menu.

This result opens the door to systematic mapping of planets' chemical evolution. In the future, by refining photochemical models and accumulating observations with JWST, we will be able to measure volatile element abundances for dozens of cool giants. Missions like ARIEL and the Roman Space Telescope will make this routine. Then we'll understand whether the universe's recipe encyclopedia is truly universal for all stars, or if exotic dishes, with flavors yet unknown, await on the outskirts of the Galaxy.