The Great Red Spot extends far deeper than planetary scientists anticipated
A 3D map of Jupiter’s atmosphere has given researchers their first view of the inner workings of the planet’s belts, zones and cyclones. The map, produced from five years of observations by NASA’s Juno spacecraft, reveals that Jupiter’s storms extend deeper than expected, including the Great Red Spot (GRS).
Juno arrived at Jupiter in July 2016 and since then it has swooped in close to the planet 37 times. During these manoeuvres, its microwave radiometer looked beneath the upper clouds, examining the structure of the planet’s storms, including the Great Red Spot (GRS). The readings found that cyclones are warmer at the top, making them less dense, while their bases are much colder. Meanwhile anticyclones such as the GRS, which spin in the opposite direction, are flipped the other way up.
Juno has also created a map of the planet’s gravitational field. As denser areas within the planet’s atmosphere have more mass, they will have a stronger gravitational pull, allowing astronomers to work out how mass is distributed.
Using this information, they calculated that most storms on Jupiter reached down further than expected – to around 100km – while the roots of the GRS travel down a huge 350km.
“The precision required to get the gravity of the GRS during the July 2019 flyby is staggering,” said Marzia Parisi from NASA’s Jet Propulsion Laboratory. “Being able to complement the microwave radiometer’s finding on the depth gives us great confidence in the results of future gravity experiments.” www.missionjuno.swri.edu
Being able to fly a spacecraft over Jupiter’s Great Red Spot and detect changes in its speed as small as 1mm per second is an impressive achievement.
Juno’s precision flying has revealed a planet that is much more complicated than we might otherwise have expected. It’s clear that what happens on the surface is influenced by what happens deep beneath the clouds, and vice versa, and understanding the planet as a whole requires attention to be paid to multiple levels at once.
This insight comes from Juno getting up close, and it’s clear that modelling Jupiter’s weather requires detailed observations.
Spare a thought for those poor astronomers trying to understand distant exoplanets. Seeing Jupiter close up reveals a dynamic and complex story; confidently understanding worlds seen, at best, as points of light is another kettle of fish entirely.
Chris Lintott co-presents The Sky at Night