At Jupiter and Saturn, Big Mysteries Remain Despite Landmark Missions

The Cassini spacecraft captured this image of Saturn in April 2016.
The Cassini spacecraft captured this image of Saturn in April 2016. (Image credit: NASA/JPL-Caltech/Space Science Institute)

It's going to take more than one milestone mission per planet for scientists to crack the mysteries of Jupiter and Saturn.

That's one scientist's conclusion about the puzzles that NASA's Cassini and Juno missions have revealed. Cassini finished its 13 years at Saturn in September 2017; Juno recently passed the halfway point in its orbits of Jupiter. Both missions have produced incredible data about the detailed workings of the two massive gas giants, and scientists have been hard at work interpreting that data.

"Although there are puzzles yet to be explained, this is already clarifying some of our ideas about how planets form, how they make magnetic fields and how the winds blow," David Stevenson, a planetary scientist at Caltech, said in a university statement released in conjunction with his presentation at this week's meeting of the American Physical Society in Boston.

Stevenson is particularly focused on data from Juno, which has been at Jupiter for two and a half years. In that time, the probe has found plenty of unexpected phenomena at the gas giant, including strange strong and weak spots in the planet's magnetic field and heavy elements spread throughout the planet.

The Cassini spacecraft captured this image of Jupiter in December 2000. (Image credit: NASA/JPL/University of Arizona)

Fortunately, the spacecraft has more than two years left in its stay, and scientists are still poring through the data gathered by its predecessor at Saturn.

"A successful mission is one that surprises us. Science would be boring if it merely confirmed what we previously thought," Stevenson said.

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Meghan Bartels
Senior Writer

Meghan is a senior writer at and has more than five years' experience as a science journalist based in New York City. She joined in July 2018, with previous writing published in outlets including Newsweek and Audubon. Meghan earned an MA in science journalism from New York University and a BA in classics from Georgetown University, and in her free time she enjoys reading and visiting museums. Follow her on Twitter at @meghanbartels.