NASA’s Juno spacecraft measured heat beneath Io’s surface for the first time, finding temperatures rise sharply within just a few feet. The data suggest heat may move through Io’s crust far faster than on Earth, or come from widespread lava flows buried beneath solid rock. The measurements could help scientists understand tidal heating, a process that powers volcanoes and may also sustain oceans inside icy moons. Io’s surface may look frozen in place from afar, but just below it, temperatures climb sharply. NASA’s Juno spacecraft has now measured that buried heat directly, exposing a world still being reshaped from within. Data from Juno’s Microwave Radiometer, or MWR, show temperatures rising by more than 40 degrees Fahrenheit within only a few feet of the surface. The measurements came from two close flybys in late 2023 and early 2024. The results, published in the Journal of Geophysical Research: Planets, mark the first direct measurements of Io’s subsurface temperature. They also offer a new way to examine how the moon releases the enormous heat generated inside it. Southwest …