Scientists at the Japanese Aerospace Exploration Agency (JAXA) have unexpectedly discovered a planetary scale ‘heat wave’ in Jupiter’s atmosphere.
The heat wave extends 130,000 kilometres, which is ten times the diameter of Earth, and reaches temperatures of 700 degrees Celsius. The heat wave’s soaring temperatures make Jupiter hundreds of degrees hotter than models have previously predicted.
The scientists discovered that the wave of heating appears to stretch from Jupiter’s Auroral Region, near the planet’s Northern pole, to its equator in the centre.
The researchers presented this exciting new discovery at the 2022 Europlanet Science Congress (ESPC) in Granada.
The complexities of Jupiter’s atmosphere
The atmosphere of Jupiter is the largest in our Solar System and is made up of mostly molecular hydrogen and helium in roughly solar proportions. Each layer has different temperature gradients and have complicated structures, which means researchers have a low understanding of the banded structure.
Famous for its characteristic, multicoloured vortices, the team have discovered that Jupiter’s atmosphere is unexpectedly hot. Because its orbital distance is millions of kilometres from the Sun, scientists’ predictions of Jupiter’s temperature have fallen hundreds of degrees short.
The gas giant receives under 4% of the amount of sunlight Earth receives, which means that theoretically, its upper atmosphere should reach freezing temperatures of minus 70 degrees.
Despite predictions about a cold upper region, the cloud tops of Jupiter’s atmosphere are measured at over 400 degrees per area.
In the same way as Earth, Jupiter experiences auroras around its poles as a result of solar wind. However, while Earth’s auroras are transient and only occur when solar activity is intense, auroras across Jupiter’s atmosphere are permanent and have a variable level of intensity.
They can become so powerful that they are able to heat the region around the poles to temperatures as high as 700 degrees, with global winds redistributing the heat equally around the planet.
Dr James O’Donoghue, of JAXA, explained: “Last year we produced and presented at EPSC 2021, the first maps of Jupiter’s upper atmosphere capable of identifying the dominant heat sources. Thanks to these maps, we demonstrated that Jupiter’s auroras were a possible mechanism that could explain these temperatures.”
The impact of Jupiter’s auroras on its atmospheric temperature
The team of researchers analysed their findings further and discovered that the ‘heat wave’ was located just below Jupiter’s northern aurora, travelling at speeds that exceeded thousands of kilometres per hour.
They concluded that the ‘heat wave’ was likely to have been triggered by a pulse of enhanced solar wind plasma impacting the magnetic field of Jupiter’s atmosphere. The researchers found that changes in the magnetic field boosted auroral heating and forced hot gases to expand, which spilled out towards the equator.
“While the auroras continuously deliver heat to the rest of the planet, these heat wave ‘events’ represent an additional, significant energy source,” O’Donoghue said.
He concluded: “These findings add to our knowledge of Jupiter’s upper-atmospheric weather and climate, and are a great help in trying to solve the ‘energy crisis’ problem that plagues research into the giant planets.”