Abstract
Using images from the Hubble Space Telescope, Nichols et al. observed oscillations in the locations of Saturn's northern and southern auroral ovals. Both auroral ovals' positions oscillate 1°–2° between dawn and dusk. While the southern auroral oval oscillation had been previously observed, the present observation, made during Saturn's 2009 equinox, is the first one that indicates that the location of the northern auroral oval oscillates with similar amplitude. The researchers also found that the locations of the auroral ovals oscillate with periods close to the rotation periods of radio emissions known as Saturn kilometric radiation (SKR). In a related paper, Gurnett et al. (Geophys. Res. Lett., 37, L24101, doi:10.1029/2010GL045796, 2010) observed changes in the rotational modulation rate of the SKR that could be controlled by changes in the planet's magnetosphere. Magnetosphere effects could cause shifting of the auroral ovals as well. (Geophysical Research Letters, doi:10.1029/2010GL045818, 2010)
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