NASA has a spacecraft orbiting Jupiter called Juno that has been toiling away for a long time now. One of the things Juno has been doing is investigating the magnetic field of the planet. Juno has discovered that the internal magnetic field of Jupiter changes over time; the phenomenon is called secular variation.
This is the first definitive detection of secular variation in a planet other than Earth. Data gathered by Juno suggests that the deep atmospheric winds of Jupiter most likely drive the secular variation. The discovery will help scientists to understand the interior structure of Jupiter, including its atmospheric dynamics.
The data could also help scientists to learn more about changes in the Earth’s magnetosphere. Scientists on the Juno project say that the discovery could only take place thanks to the extremely accurate science instruments onboard Juno and its orbit. Juno’s orbit carries it low over the planet as it travels pole to pole.
Scientists working with the new data compared it to data gathered from past Jupiter mission, including data gathered by Pioneer 10 and 11 as well as Voyager I and Ulysses. Juno data was used to create a new model of the magnetic field of Jupiter called JRM09. That model was based on data collected during the first eight science passes Juno made of Jupiter using its magnetometer.
That tool can generate a 3D map of the magnetic field of the planet. Once the team proved that secular variation did occur on Jupiter, it set about figuring out how. It says that the operation of Jupiter’s atmospheric winds best explains the variations. The wind extends from the surface of the planet to 1,860 miles deep where the planet’s interior lies. The most variation was found in something called the great blue spot where the planet has particularly strong winds.