The long-term steady motion of Saturn's hexagon and the stability of its enclosed jet stream under seasonal changes
Article first published online: 7 MAR 2014
©2014. American Geophysical Union. All Rights Reserved.
Geophysical Research Letters
Volume 41, Issue 5, pages 1425–1431, 16 March 2014
How to Cite
2014), The long-term steady motion of Saturn's hexagon and the stability of its enclosed jet stream under seasonal changes, Geophys. Res. Lett., 41, 1425–1431, doi:10.1002/2013GL059078., et al. (
- Issue published online: 2 APR 2014
- Article first published online: 7 MAR 2014
- Accepted manuscript online: 14 FEB 2014 08:20AM EST
- Manuscript Accepted: 10 FEB 2014
- Manuscript Revised: 4 FEB 2014
- Manuscript Received: 18 DEC 2013
- polar regions
We investigate the long-term motion of Saturn's north pole hexagon and the structure of its associated eastward jet, using Cassini imaging science system and ground-based images from 2008 to 2014. We show that both are persistent features that have survived the long polar night, the jet profile remaining essentially unchanged. During those years, the hexagon vertices showed a steady rotation period of 10 h 39 min 23.01 ± 0.01 s. The analysis of Voyager 1 and 2 (1980–1981) and Hubble Space Telescope and ground-based (1990–1991) images shows a period shorter by 3.5 s due to the presence at the time of a large anticyclone. We interpret the hexagon as a manifestation of a vertically trapped Rossby wave on the polar jet and, because of their survival and unchanged properties under the strong seasonal variations in insolation, we propose that both hexagon and jet are deep-rooted atmospheric features that could reveal the true rotation of the planet Saturn.