Saturn has its rings, Mars has its rusty landscape, Earth has its whales, water, and wi-fi…and Jupiter has its Great Red Spot. The giant gas planet’s enormous orange storm—once over twice the diameter of Earth but today “only” about 1.3 times as wide—is one of the most distinctive planetary features in our Solar System. It’s so well-known that even young children are sure to include its orangey oval when drawing Jupiter!
But as famous as it is, there’s a lot we still don’t know about Jupiter’s giant storm. NASA’s Juno spacecraft, launched in August 2011, has now been orbiting Jupiter since July 4, 2016 and has been using its suite of science instruments to investigate the planet’s complex atmosphere like never before possible. Thanks to Juno, for the first time scientists are able to “see” deep below Jupiter’s dense clouds (in microwave wavelengths, that is) and find out what’s happening inside the GRS. What they’ve discovered is a storm hundreds of miles deep with a hot base that powers its winds.
“One of the most basic questions about Jupiter’s Great Red Spot is: how deep are the roots? Juno data indicate that the Solar System’s most famous storm is almost one-and-a-half Earths wide, and has roots that penetrate about 200 miles (300 kilometers) into the planet’s atmosphere.”
— Scott Bolton, Juno principal investigator, SwRI
The video below takes the viewer on a simulated flight into, and then out of, Jupiter’s Great Red Spot. It was created by combining an image from JunoCam with a computer-generated model of Jupiter’s clouds.
“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. “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.”
Returns of the JEDI
Juno has also “used its JEDI powers” to discover a new radiation zone around Jupiter (as if it needed even more of a radiation environment!) Juno’s JEDI—which stands for Jupiter Energetic Particle Detector Instrument—has detected a belt of high-velocity ions above Jupiter’s equator during its close “perijove” fly-overs (the next of which, P10, will occur on Dec. 16.) The ions are thought to originate as neutral atoms from moons Io and Europa and become energized when they interact with the upper layers of Jupiter’s atmosphere.
“The closer you get to Jupiter, the weirder it gets,” said Heidi Becker, Juno’s radiation monitoring investigation lead at JPL. “We knew the radiation would probably surprise us, but we didn’t think we’d find a new radiation zone that close to the planet.”
Just like its mythological namesake, Juno is demonstrating its amazing ability to reveal the clandestine behaviors of giant Jupiter. It will be interesting to see what 2018 brings with another year of perijove peeks!