Tuesday, July 17, 2018

Terrawatch: Nasa hopes Juno will reveal the heart of Jupiter

Data from Juno may show whether there is a solid core at the centre of Jupiter
Jupiter’s southern hemisphere captured by Nasa’s Juno spacecraft during a close fly-by of the planet. Photograph: Kevin M Gill/MSSS/SWRI/JPL-Caltech/Nasa/AFP/Getty Images
Earth’s crust and oceans give our planet an obvious boundary. But jump to Jupiter and no such edge is visible. Instead, its gaseous atmosphere gradually compresses until it becomes a liquid.

No one knows if there is a solid core at its centre. But with luck, data coming back from Nasa’s ambitious Juno mission will reveal what lies at Jupiter’s heart. Already images of exquisite swirling cloud tops have been beamed back, and the accompanying data reveals strong local variations in magnetic and gravity fields on the planet. “The most likely way this could occur is that strong winds deep below the cloud surface are disturbing these fields,” explains Gary Glatzmaier from the University of California.

His recent computer simulations (published last week in PNAS) suggest that long-observed strong east-west winds extend deep into the interior, twisting and shearing the magnetic field.

Glatzmaier chose to include a small solid inner core in his model, and was surprised to see that the presence of this core produced two oscillating jet stream winds at the surface. Now he is waiting eagerly, to see if any of Juno’s forthcoming close fly-bys will reveal these oscillating jet streams, and confirm the presence of a core.

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