Slashdot Mirror
NASA Spacecraft Reveals Jupiter's Interior In Unprecedented Detail (theguardian.com)
NASA's Juno spacecraft has revealed that Jupiter's iconic striped bands, caused by immensely powerful winds, extend to a depth of about 3,000km below the surface. The findings also provide a partial answer to the question of whether the planet has a core, "showing that the inner 96% of the planet rotates 'as a solid body,' even though technically it is composed of an extraordinarily dense mixture of hydrogen and helium gas," reports The Guardian. From the report: The findings are published in four separate papers in the journal Nature, describing the planet's gravitational field (surprisingly asymmetrical), atmospheric flows, interior composition and polar cyclones. A crucial question was whether the bands on Jupiter, caused by air currents that are five times as strong as the most powerful hurricanes on Earth, were a "weather" phenomenon comparable to the Earth's jet streams or part of a deep-seated convection system. Juno's latest observations point to the latter, showing the jets continued to around 3,000km beneath the surface -- deep enough to cause ripples and asymmetries in the planet's gravitational field that were perceptible to detectors on the spacecraft. On Earth, the atmosphere represents about a millionth of the mass of the whole planet. The latest work suggests that on Jupiter the figure is closer to 1%. The new findings, based on extremely sensitive gravitational measurements, also begin to paint a picture of the internal structure of the planet.
For general information, the surface is said (by consensus) to be the depth at which the atmospheric pressure is the same as that at sea level on Earth. There is no adjustment for gravity nor temperature. That is, it is pressure and not density. I mention this since it isn't obvious what "surface" means when applied to gas giants (or stars, for that matter - although stars have a completely different (and incompatible) definition for their "surface".)