Planet-sized heat wave found in Jupiter’s atmosphere: ScienceAlert

A heat wave the size of 10 terrestrial planets has been detected spreading through Jupiter’s atmosphere.

It was 130,000 kilometers (about 81,000 miles) wide, and 700 °C (1,292 °F), traveling at up to 2,400 meters per second away from the Jovian North Pole.

And that, scientists say, could solve one of the most vexing mysteries about the largest planet in our solar system – why it’s so much hotter than models predict.

It’s the perpetual auroras shining at Jupiter’s poles that could provide additional energy to heat the gas giant to temperatures well beyond what we expect—and most likely, combined with intense solar winds, are responsible for the surging heat wave.

“Last year, we produced … the first maps of Jupiter’s upper atmosphere capable of identifying the sources of the prevailing heat,” says astronomer James O’Donogh of the Japan Aerospace Exploration Agency (JAXA) in Japan.

“Thanks to these maps, we showed that Jupiter’s aurora borealis was a potential mechanism that could explain these temperatures.”

The first idea that something strange was happening in Jupiter’s atmosphere came in the 1970s, about 50 years ago.

Jupiter is much farther from the Sun than Earth; Almost five times the distance, in fact. From that distance, it receives only four percent of the solar radiation that reaches Earth.

The average upper atmosphere temperature should be around -73 degrees Celsius (-99 degrees Fahrenheit). Instead, it lies at about 420 degrees Celsius – comparable to Earth’s upper atmosphere, much higher than can be explained by solar heating alone.

This means there must be something else going on at Jupiter, and the first heat maps, obtained by O’Donoghue and his colleagues and published last year, suggest a solution.

Jupiter crowns the most powerful auroras in the solar system, glowing in wavelengths invisible to the human eye. We also know that the aurora borealis here on Earth causes significant heating of our atmosphere.

Jupiter’s auroras are much like Earth’s auroras: an interaction of charged particles, magnetic fields, and particles in the planet’s atmosphere. They are also very alien. The aurora borealis on Earth are generated by the blowing of particles from the strong solar wind. It’s discontinuous, and it depends on those irregular inputs.

Jupiter’s aurora borealis are permanent, generated by particles from its moon Io, the most volcanic body in the Solar System, which constantly causes sulfur dioxide to erupt. This forms a hoop of plasma around Jupiter, which is directed to its poles through magnetic field lines, where it rains into the atmosphere.

Voila – Twilight. Previous heat maps of Jupiter have revealed hot spots just below the auroral oval, suggesting a link between the two.

But then it got more interesting. Io’s contribution does not mean that there is no auroral contribution from the Sun, which O’Donoghue and colleagues have observed.

While they were collecting observations of Jupiter and strange temperatures, a dense solar wind collided with the gas giant. As a result, the team noticed an improvement in the auroral heat.

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As the hot gas expands, this is likely what sent the heat wave leaking out of the auroral oval and rolling toward the equator at thousands of kilometers per hour.

Therefore, during its propagation, this could have increased the heat of the atmosphere by a significant amount.

“While the aurora borealis constantly transfers heat to the rest of the planet, these heat wave events represent an important additional source of energy,” O’Donoghue explains.

“These findings add to our knowledge of weather and climate in Jupiter’s upper atmosphere, and are a huge help in trying to solve the ‘energy crisis’ that has plagued research on giant planets.”

Jupiter isn’t the only planet in the solar system that’s hotter than it should be. Saturn, Neptune, and Uranus are hundreds of degrees hotter than solar heating can explain.

While none of the others have auroras on the scale of Jupiter, this discovery represents an avenue of exploration that might go some way toward solving the mystery.

The team presented their findings at the 2022 Europlanet Science Conference.

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