Louis-Philippe Coulombe

Planet WASP-121b orbits so near its star that the fierce heat boils its atmosphere away, streaming like a comet's tails. With the James Webb Space Telescope, astronomers continuously watched this process for the first time.

Planet WASP-121 b always shows the same face to its star, like a rock in a campfire. The dayside is so hot that ordinary hydrogen, the very stuff most of the universe is made of, can't take it: its molecules tear apart into individual atoms, and the temperature flips upside down: the higher you go, the hotter it gets.

WASP-121 b is not just a hot ball. It's a world where iron vaporizes and the sky glows with its own heat. A fresh look at it has revealed what 'ingredients' went into making it. The James Webb Space Telescope has for the first time clearly detected vaporized silicon monoxide in its atmosphere — a refractory substance usually locked inside dust grains.