Jupiter's Great Red Spot 'roars with heat'

Jupiter's Great Red Spot - a hurricane three times bigger than Earth - is blasting the planet's upper atmosphere with heat, astronomers have found.

Using measurements from an infrared telescope in Hawaii, a UK and US team found evidence for temperatures as high as 1,500C - hundreds of degrees warmer than anywhere else on the planet.

They suggest the hotspot is created by thunderous soundwaves "breaking" in the thin upper reaches of the atmosphere.

The research is published in Nature, BBC News reports.

It arguably solves what planetary scientists had dubbed an "energy crisis" for gas giants like Jupiter: temperatures in their upper atmospheres soar much higher than can be explained by solar energy - especially given their vast distances from the Sun.

If the mysterious heat were generated by local sources, like Jupiter's famous storm, then the conundrum would be solved - and these measurements are the first direct evidence of any such activity.

Study co-author Dr Tom Stallard, from the University of Leicester, said this was a major step forward in a "20-30 year odyssey" to try and understand heat flow on Jupiter.

"Ever since Voyager, we've had measurements of the temperature at the top of Jupiter's atmosphere, and it's been hot across the whole globe - from the poles, all the way to the equator," he told the BBC.

Jupiter's enormous, dramatic aurora can explain the heat in the polar regions, but for that warmth to reach the equator would require incredibly dramatic mixing, which modelling studies haven't been able to support.

"There's no real excuse for it to be so hot," said Dr James O'Donoghue from Boston University, the paper's first author.

The freshly discovered spike in temperature, detected using a spectrometer at the Nasa Infrared Telescope Facility (IRTF) in Mauna Kea, Hawaii, offers a solution.

Several hundred km directly above the clouds of the Great Red Spot, the hotspot suggests that high-altitude heat is somehow created by the turmoil beneath.

"Several people have argued that it's likely that the heat comes from below, but the observations have never backed them up," Dr Stallard said.

He and his colleagues don't know exactly what is causing the heat, but they have some ideas. It could be driven by devastating Jovian thunderclaps, rumbling upwards from the churning red clouds of the Solar System's biggest storm.