Carbon dioxide gas spotted in atmosphere of Jupiter’s moon Callisto

Astronomers have spotted gaseous carbon dioxide across the atmosphere of Jupiter’s second-largest moon, Callisto, hinting that it might have a much more complex carbon cycle than we thought. On Earth, the carbon cycle helps to sustain a stable climate.

Callisto is one of the solar system’s oldest objects, having formed some 4.5 billion years ago around Jupiter. It is also one of the most battered objects, with a surface blanketed by craters.…