韦布空间望远镜一窥木卫四的古老伤痕

木卫四（Callisto）常被视为伽利略卫星中最沉寂的一颗，其表面布满了古老的撞击坑。然而，来自韦布空间望远镜（JWST）的最新数据表明，这颗卫星的活跃程度远超以往的认知。

Of Jupiter’s four Galilean moons, Callisto is the one that gets the least attention. Io is constantly being resurfaced by volcanoes. Europa has a giant liquid water ocean. And Ganymede has its own magnetic field that interacts with its parent planet in weird ways. Callisto, by comparison, seems sedate, with its ancient, crater-saturated surface seemingly frozen in time. But new data from the James Webb Space Telescope (JWST) shows that even this most benign of the Big Four moons is more active than previously realized.