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

A heat wave the size of 10 Earths has been discovered in Jupiter’s atmosphere.

It was 130,000 kilometers (about 81,000 miles) in diameter and a scorching 700 degrees Celsius (1,292 degrees Fahrenheit), moving at speeds of up to 2,400 meters per second from the Jovian north pole.

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

It’s the permanent auroras twinkling at Jupiter’s poles that could provide the extra energy to heat the gas giant to temperatures far beyond what we expect – and likely, with a dense solar wind, responsible for the heat wave.

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

“Through these maps, we demonstrated that Jupiter’s auroras were a possible mechanism that could explain these temperatures.”

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

Jupiter is much farther from the Sun than Earth; about five times the distance, in fact. At this distance, it receives only 4% of the solar radiation that reaches the Earth.

Its upper atmosphere is expected to have an average temperature of around -73 degrees Celsius (-99 degrees Fahrenheit). Instead, it sits at around 420 degrees Celsius – comparable to Earth’s upper atmosphere, and much higher than solar heating alone can explain.

This means that there must be something else going on at Jupiter, and the first heatmaps, obtained by O’Donoghue and his colleagues and published last yearindicated a solution.

Jupiter is crowned by the most powerful auroras in the solar system, bursting into wavelengths invisible to the human eye. We also know that auroras here on Earth cause non-negligible heating of our own atmosphere.

Jupiter’s auroras are very similar to those on Earth: an interaction between charged particles, magnetic fields and molecules in the planet’s atmosphere. And they are also very alien. Earth’s auroras are born from bursts of particles blown by powerful solar winds. They are sporadic, dependent on this irregular supply.

Jupiter’s auroras are permanent, generated by particles from its moon Io, the most volcanic object in the solar system, which constantly spews sulfur dioxide. This forms a torus of plasma around Jupiter, which is routed to its poles via magnetic field lines, where it rains down into the atmosphere.

And There you go – dawn. Past heat maps of Jupiter have revealed hotspots directly beneath the auroral oval, suggesting a connection between the two.

But then it got more interesting. The contribution from Io does not mean that there is no auroral contribution from the Sun, and this is what O’Donoghue and his colleagues observed.

As they collected observations of Jupiter and its bizarre temperatures, a dense solar wind slammed into the gas giant. As a result, the team observed an improvement in auroral heating.

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Because the hot gas is expanding, that’s likely what sent the heat wave spilling out of the auroral oval and rolling toward the equator at speeds of up to thousands of miles per hour.

So as it spread, it would have provided a significant amount of additional heat to the Jovian atmosphere.

“While the aurora continuously provides heat to the rest of the planet, these heat wave ‘events’ represent an additional and significant source of energy,” O’Donoghue explains.

“These findings add to our knowledge of the weather and climate of Jupiter’s upper atmosphere, and are of great help in trying to solve the problem of the ‘energy crisis’ plaguing giant planet research.”

Jupiter is not the only planet in the solar system to be hotter than it should be. Saturn, Neptune and Uranus are all hundreds of degrees hotter than solar heating can account for.

While none of the others have Jupiter-scale auroras, this discovery represents a avenue of exploration that could help solve the puzzle.

The team presented its findings to the Europlanet Science Congress 2022.

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