In a new paper out today in Nature, researchers from Boston University explain how they constructed a heat-map of the atmosphere using infrared emissions thrown off by the planet. With that heat map, researchers were able to trace the temperature spike to its source. The highest temperatures were consistently over the planet’s Great Red Spot, an ever-present storm system larger than two Earths.

Researchers had previously flagged the turbulent storm as a potential heat source but, until this study, had no way to back up their hunch. Now that this team pinned the heat to a likely source, though, researchers have even more questions.

The precise mechanism by which the storm system’s heat transfer works, for instance, has yet to be uncovered. Equally intriguing is the question of what will happen to Jupiter’s atmosphere as the Great Red Spot changes. This “perpetual hurricane,” as researchers describe it, has raged for centuries at least—but that doesn’t mean it’s going to keep on going forever. Previous studies have shown that the giant spot appears to be steadily shrinking with age.