Magnetic field data: Thin atmosphere on Saturn's moon Dione



A new study indicates that Dione, one of Saturn's moons, probably has a tenuous atmosphere. NASA's Cassini spacecraft has conducted only two close flybys of Dione. Magnetic field observations from one of those flybys, described by Simon et al., show evidence of an atmospheric interaction with magnetospheric plasma. The authors used a model to demonstrate that a low-density atmosphere would explain the magnetic field data. (Geophysical Research Letters, doi:10.1029/2011GL048454, 2011)