Note: This is a press release from Jet Propulsion Laboratory.

Bob Eklund
Looking Up

NASA’s Juno spacecraft will make its long anticipated arrival at Jupiter on July 4. Coming face-to-face with the gas giant, Juno will begin to unravel some of the greatest mysteries surrounding our solar system’s largest planet, including the origin of its massive magnetosphere.

Magnetospheres are the result of a collision between a planet’s own magnetic field and the supersonic solar wind. Jupiter’s magnetosphere—the volume carved out in the solar wind where the planet’s magnetic field dominates—extends some 2 million miles outward from the planet’s surface.

To look inside the planet, the team equipped Juno with a pair of magnetometers—instruments that record both the direction and magnitude of magnetic fields—which will allow high-accuracy mapping of Jupiter’s magnetic field.

One of the mysteries the team hopes to answer is how Jupiter’s magnetic field is generated. Scientists expect to find similarities between Jupiter’s magnetic field and that of Earth.

Magnetic fields are produced by what are known as dynamos—convective motion of electrically conducting fluid inside planets. As a planet rotates, the electrically susceptible liquid swirls around and drives electric currents, inducing a magnetic field. Earth’s magnetic field is generated by liquid iron in the planet’s core.

NASA scientists expect Juno’s magnetometers to be able to see through Jupiter’s outer gaseous envelope, made of hydrogen and helium, and get a clear view of its dynamo.