Astronomy Picture of the Day

Explanation: How similar is Jupiter's magnetic field to Earth's? NASA's robotic Juno spacecraft has found that Jupiter's magnetic field is surprisingly complex, so that the Jovian world does not have single magnetic poles like our Earth. A snapshot of Jupiter's magnetic field at one moment in time, as animated from Juno data, appears in the featured video. Red and blue colors depict cloud-top regions of strong positive (south) and negative (north) magnetic fields, respectively. Surrounding the planet are imagined lines of constant magnetic field strength. The first sequence of the animated video starts off by showing what appears to be a relatively normal dipole field, but soon a magnetic region now known as the Great Blue Spot rotates into view, which is not directly aligned with Jupiter's rotation poles. Further, in the second sequence, the illustrative animation takes us over one of Jupiter's spin poles where red magnetic hotspots are revealed to be extended and sometimes even annular. A better understanding of Jupiter's magnetic field may give clues toward a better understanding of Earth's enigmatic planetary magnetism.