Above Jupiter’s Great Red Spot, where nonstop thunderstorms rumble and roil, it’s hotter than the hottest lava on Earth, reaching temperatures of at least 2400°F (1300°C).
It’s “the hottest temperature we’ve seen anywhere on the planet, in the upper atmosphere,” says study author James O’Donoghue of Boston University.
How, exactly, the solar system’s largest storm manages to bake the gassy layers above it hasn’t quite been worked out. But it’s likely that sound waves generated by those crashing storms travel upward and heat the atmosphere, scientists suggest today in Nature.
The new observations could help solve a long-standing problem in planetary science.
For years, measurements of the outer planets’ atmospheric temperatures have been too high to be explained by sunlight alone. At Jupiter, for example, the sun’s warmth should heat the outer atmosphere to roughly 80°F (26°C).
But at between 800° and 1340°F (420° and 720°C), this atmospheric region can be significantly warmer than scientists expect based on sunlight alone. And even though scientists know the planet’s spectacular auroras are heating its poles, they can’t account for Jupiter’s overall warmth.
“We call this the energy crisis nowadays, because it’s been unresolved since the 1970s at Jupiter, Saturn, Uranus, and Neptune,” O’Donoghue says.
Sound and Fury
Now observations made with the NASA InfraRed Telescope Facility in Hawaii suggest that at least one furnace is churning away and producing a localized—albeit giant—hot spot. It’s centered over Jupiter’s Great Red Spot, where storms at least as wide as Earth have been thundering away for centuries.
O’Donoghue and his colleagues looked at a particular form of hydrogen called H3+ that lives high in Jupiter’s atmosphere.
Based on the relative intensity of infrared light emitted by that ion, they could work out the temperature of the gas where it lives. And in the region around 500 miles (804 kilometers) above the Great Red Spot, it’s definitely toasty.
The team suspects that acoustic—or sound—waves produced by the spot’s thunderstorms could be heating the upper atmosphere as they shake and vibrate Jupiter’s gases.
However, it’s unlikely the Great Red Spot is warming the entire planet, meaning that the mystery of Jupiter’s overall temperature persists. But the discovery hints that smaller thunderstorms and other atmospheric turbulence scattered throughout Jupiter could be contributing to its overall temperature, O’Donoghue suggests.
The observation marks the first time an instrument sensitive enough to resolve individual hot spots was aimed at the solar system’s largest planet—and that may help us figure out more about our own home world.
“Jupiter is like a giant laboratory for extreme physics,” says O’Donoghue. “It’s teaching us how storms interact with the upper atmosphere in a way that is difficult to measure on Earth.”
For instance, something similar may be occurring over large mountain ranges, although to a lesser extent. Thunderstorms on our planet are thankfully transient (and not several Earths wide) yet winds gusting into and over mountains could also generate acoustic waves capable of heating the skies above.
“We suggested that this could be a plausible mechanism for a hot spot observed slightly eastward of the Andes mountains,” says Michael Hickey of Embry-Riddle Aeronautical University. “Other places on Earth that this might occur would be the Alps and the Himalaya.”
The observations and proposed mechanism are certainly intriguing, says Amy Simon of NASA’s Goddard Space Flight Center. But she suggests viewing the measured temperatures with caution, noting that interpreting the signals from H3+ molecules is quite tricky, and higher-resolution data would be helpful.
O’Donoghue agrees, and says the team gathered more data earlier this year that are still being analyzed. For now, at least, it appears as though the Great Red Spot is a sweltering place indeed.
“Perhaps the hot area above the Great Red Spot is the ideal place to catch a Charizard,” O’Donoghue adds.