NASA’s Juno probe has discovered that Jupiter’s Great Red Spot has roots that descend deep into the planet.
The storm has been raging for at least 350 years, covering an area 16,000 kilometers (10,000 miles) wide, which is 1.3 times bigger than Earth. The findings were announced on Monday, December 11, at the annual American Geophysical Union meeting in New Orleans.
Thanks to Juno, we’ve been able to get a greater handle on its depth for the first time. The Microwave Radiometer (MWR) instrument on the spacecraft was able to peer deep beneath the clouds and see how far down it extended.
And that revealed that the storm penetrates about 300 kilometers (200 miles) into the planet’s atmosphere, well below the upper clouds we can see in images. This data was collected in July 2017, when Juno flew over the storm for the first time.
"Juno found that the Great Red Spot's roots go 50 to 100 times deeper than Earth's oceans and are warmer at the base than they are at the top," said Andy Ingersoll, professor of planetary science at Caltech and a Juno co-investigator, in a statement. "Winds are associated with differences in temperature, and the warmth of the spot's base explains the ferocious winds we see at the top of the atmosphere."
Scientists aren’t sure at the moment what will happen to the Great Red Spot in the future, but it appears to be shrinking. It has been monitored since 1830, and since then it has shrunk from more than two times the width of Earth to 1.3 today.
Data from Juno’s Jupiter Energetic Particle Detector Instrument (JEDI) also revealed a previously uncharted radiation zone around Jupiter. One is just above the gas giant’s atmosphere near the equator, and includes energetic hydrogen, oxygen, and sulphur ions moving near to the speed of light. This may be the result of gas around Io and Europa.
Juno is continuing to orbit Jupiter, and has so far completed eight science flybys. It takes 53 days for the spacecraft to orbit the planet in a wide sweeping trajectory that keeps it mostly outside of Jupiter’s intense radiation apart from these close flybys.
It comes as close to 3,400 kilometers (2,100 miles) from the planet during its closest approaches, when its instruments are switched on to gather data. Its next pass will take place on December 16, and the mission is expected to continue until at least July 2018.