Astronomers couldn't understand why the 'hot Neptune desert' — a region right next to stars — has almost no Neptune-sized planets. It was thought that there they are doomed: the star's proximity boils off the atmosphere, leaving a bare rocky core. But the exoplanet LTT-9779 b, 29 times heavier than Earth and with a 19-hour orbit, survived. The James Webb Space Telescope peered into its heat-blasted world.

Using spectral analysis and transit observations across the star's disk, scientists discovered that the atmosphere is packed with carbon — carbon monoxide and carbon dioxide. There is tens of thousands of times more of these than water vapor. The carbon-to-oxygen ratio is nearly one, and heavy elements are 500 times more abundant than in the Sun. This mixture prevents the planet from evaporating: heavy molecules, like cocoon threads, firmly hold the gas envelope. Meanwhile, LTT-9779 b reflects 80% of light — it's the shiniest known exoplanet, a giant mirror in space. David Charbonneau, pioneer of the transit method, never imagined planets could be this cunning.