Probing Jupiter’s big magnetic bubble
By Ron Cowen
Simultaneous measurements by two spacecraft have probed in greater detail than ever before the invisible bubble of charged particles that surrounds Jupiter.
The bubble, or magnetosphere, is the solar system’s largest structure with sharp boundaries and has a diameter greater than 100 times that of the giant planet.
The data were obtained early last year when the Galileo probe, which has orbited Jupiter and its moons since 1995, was briefly joined by the Cassini craft, which flew past the planet on its way to Saturn. The combined information shows that the magnetosphere contracts in response to shock waves from the sun.