Reza Ashtari

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.

Hundreds of light-years away, there's a planet that looks like a giant mirror. LTT9779b reflects most of the light that hits it — far more than you'd expect from a Neptune-sized body. Astronomers have long debated what makes it so shiny: a thick carbon-rich haze or a layer of clouds. The James Webb Space Telescope has helped settle the debate.