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The Juno science team today released their first research results since the spacecraft entered orbit around Jupiter in July 2016.
“Although many of the observations have terrestrial analogs, it appears that different processes are at work creating the auroras,” said SwRI’s Dr. Phil Valek, JADE instrument lead. “With JADE we’ve observed plasmas upwelling from the upper atmosphere to help populate Jupiter’s magnetosphere. However, the energetic particles associated with Jovian auroras are very different from those that power the most intense auroral emissions at Earth.”
Also surprising, Jupiter’s signature bands disappear near its poles. JunoCam images show a chaotic scene of swirling storms up to the size of Mars towering above a bluish backdrop. Since the first observations of these belts and zones many decades ago, scientists have wondered how far beneath the gas giant’s swirling façade these features persist. Juno’s microwave sounding instrument reveals that topical weather phenomena extend deep below the cloudtops, to pressures of 100 bars, 100 times Earth’s air pressure at sea level.
“However, there’s a north-south asymmetry. The depths of the bands are distributed unequally,” Bolton said. “We’ve observed a narrow ammonia-rich plume at the equator. It resembles a deeper, wider version of the air currents that rise from Earth’s equator and generate the trade winds.”
Juno is mapping Jupiter’s gravitational and magnetic fields to better understand the planet’s interior structure and measure the mass of the core. Scientists think a dynamo — a rotating, convecting, electrically conducting fluid in a planet’s outer core — is the mechanism for generating the planetary magnetic fields. “Juno’s gravity field measurements differ significantly from what we expected, which has implications for the distribution of heavy elements in the interior, including the existence and mass of Jupiter’s core,” Bolton said. The magnitude of the observed magnetic field was 7.766 Gauss, significantly stronger than expected. But the real surprise was the dramatic spatial variation in the field, which was significantly higher than expected in some locations, and markedly lower in others. “We characterized the field to estimate the depth of the dynamo region, suggesting that it may occur in a molecular hydrogen layer above the pressure-induced transition to the metallic state.”
What I want to see is a depth map showing where Jupiter’s atmosphere ends and its solid core begins. I expect Juno will eventually be able to give us a first glimpse.