Hot Jupiters are giant planets, puffed up like balloons. Scientists have found they’re heated not by deep internal warmth, but by surface heating — as if the air inside were warmed from outside. This discovery shifts how we view the climate of these worlds. What other secrets do their atmospheres hide?
Hot Jupiters—exoplanets giants snuggled up to their stars—are mysteriously puffed up. Their radii often exceed standard models by 50–100%. New models, based on transiting data (transit method), flip our understanding: heat doesn't come from the interior but from the upper atmosphere. Think of soup: if you heat only the surface, a thin layer boils while the rest stays cool. Similarly, heat gets trapped at the top, slowing interior cooling by 95–98%. This swelling can persist for eons. Even wilder: at 1500°C winds whip up, but at 1800°C they abruptly stop—like the planet overheats and turns off its own storm.
🎯 Some hot Jupiters complete an orbit around their star in less than an Earth day—on such a planet, a year is shorter than a day!