It's not every day that a hunk of metal hurtles into a planet's magnetosphere. But that's what happened yesterday when Juno—the NASA spacecraft on a mission to learn more about the origins of the solar system—entered orbit around Jupiter. And among the invaluable data the craft has already beamed back is something beyond images and measurements: sound.
As NASA reports on its blog, the Waves instrument on Juno recorded what happened when the craft swung into orbit. In its extensive review of the craft’s on-deck instrumentation, Spaceflight 101 explains that Waves is a radio and plasma sensor instrument that uses coils and receivers to help researchers understand how Jupiter interacts with its atmosphere and what’s going on in the planet’s magnetic field and magnetosphere.
When Juno was traveling through space, it was affected by the interplanetary magnetic field—a huge, spiraling field that the Sun's solar winds carry toward the planets. But when the craft locked into Jupiter’s orbit, it changed environments, too. First, it passed into the “bow shock,” an area right outside of the gas giant’s magnetosphere. As it did, it experienced a sonic-boom like jolt of turbulence as it encountered the magnetosheath—the furthest part of Jupiter’s magnetic field.
About 26 seconds into the video above, you can hear the jolt Juno experienced when it transitioned from a space filled with solar winds to Jupiter’s bow shock on June 24. But that wasn’t the only sonic stun in store: The next day, Juno passed Jupiter’s magnetopause—the true boundary between the sun’s magnetic field and that of Jupiter. At about 55 seconds in, you can hear a bizarre, sci-fi-like sound that represents the huge planet’s magnetic field. Jupiter’s magnetic field is ten times stronger than Earth’s and its magnetosphere is ginormous—a million times the volume of Earth’s and even wider than the Sun’s.
Scientists have long known that Jupiter is noisy: The planet produces intense radio storms powered by interactions between the planet and its moons, not to mention the wild gases at play on the planet itself. But they didn’t realize that Juno’s entry into Jupiter’s orbit would produce such complex data.
“While this transition from the solar wind into the magnetosphere was predicted to occur at some point in time,” the agency writes in the blog post, “the structure of the boundary between those two regions proved to be unexpectedly complex, with different instruments reporting unusual signatures both before and after the nominal crossing.” Now researchers get to try to figure out why the sounds of Jupiter are so unexpected—and the rest of us get to enjoy the strangely sonorous ride.