The atmosphere of Jupiter is hundreds of degrees hotter than expected, and astronomers think they finally know why.
The cause of the warming seems to be the Great Red Spot (GRS), the largest hurricane in the Solar System. Using NASA's Infrared Telescope Facility in Hawaii, a British-American team discovered that the atmosphere above the GRS is both warm enough and the storm powerful enough to explain the 600°C (1,112°F) temperature excess seen on Jupiter.
On Earth, the surface and atmospheric temperatures are regulated by solar radiation, but in the outer Solar System, internal processes must become dominant. A simulation by the team showed that using sunlight alone would put the Jovian atmosphere below freezing.
“With solar heating from above ruled out, we designed observations to map the heat distribution over the entire planet in search for any temperature anomalies that might yield clues as to where the energy is coming from,” lead author James O’Donoghue from Boston University explained in a statement.
O’Donoghue performed observations of Jupiter with NASA’s SpeX instrument to look at the infrared emissions of the planet. Jupiter’s southern hemisphere had some weird heating signature at certain longitudes and latitudes, and the cause was found to be the GRS.
The GRS is an incredible feature of the planet. It is large enough to contain more than two Earths, and it is an enormous source of energy. It pumps heat from the planet's interior directly into the atmosphere, where it is then propagated by waves around the planet. This study, published in Nature, provides the first evidence of the effects of the GRS on the higher altitude of the planet.
“Energy transfer to the upper atmosphere from below has been simulated for planetary atmospheres, but not yet backed up by observations,” O’Donoghue said. “The extremely high temperatures observed above the storm appear to be the ‘smoking gun’ of this energy transfer, indicating that planet-wide heating is a plausible explanation for the ‘energy crisis.’“
This discovery goes beyond Jupiter itself. Unusually high temperatures are common in other gas planets in the Solar System, and it might be a shared feature of gas giants around other stars too. As it turns out, terrific atmospheric events like this might be the cause.