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Juno Delivers

Jupiter’s Secrets

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NASA’S ONGOING JUNO MISSION, revealing what lies beneath

Jupiter’s cloud tops and in its atmosphere, has upended

many long-held theories about the king of the planets. “In

many ways, it’s a new Jupiter,” says Scott Bolton, Juno’s principal

investigator at the Southwest Research Institute in San Antonio.

Many scientists had thought that by peering underneath Jupiter’s

visibly divided outer layers, they would uncover a uniform,

well-mixed planet. But according to a May study in Geophysical

Research Letters, Juno has spied strong bands of what appears to

be ammonia, indicating the planet is churning up material from its

depths and implying a more active and variable world. The probe’s

data also show polar regions swarming with unforeseen storms.

At the same time, Juno is busy sampling Jupiter’s magnetic field,

which is stronger than expected in some places and weaker in

others, astronomers announced in the May issue of Science. And

the auroras that light up its atmosphere arise not just from charged

solar particles slamming into the planet’s atmosphere, as on Earth,

but from Jovian moons spewing material toward the planet.

So far, Juno’s discoveries raise more questions than answers, and

scientists are eager to untangle them. “We’re slowly going to rewrite

the book,” Bolton predicts. — KOREY HAYNES

FROM TOP: NASA; NASA/JPL/SWRI/MSSS/GERALD EICHSTÄDT/ALEXIS TRANCHANDON/SOLARIS; NASA/JPL/SWRI/MSSS/BJÖRN JÓNSSON

Photos from Juno’s orbit of Jupiter reveal

amazing vistas. Above, the gas giant’s northern

pole area roils with white clouds. Below, the

stormy dynamics of the Great Red Spot are

visible during a low-altitude pass.