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Science 16 April 1993:
Vol. 260. no. 5106, pp. 329 - 332
DOI: 10.1126/science.260.5106.329
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Articles

Ground-Based Observations of Saturn's North Polar Spot and Hexagon

A. Sanchez-Lavega 1, J. Lecacheux 2, F. Colas 3, and P. Laques 4

1 Departamento Fisica Aplicada I, Escuela Técnica Superior de Ingenieros Industriales y de Telecomunicación, Universidad del País Vasco, Alda. Urquijo s/n, 48013 Bilbao, Spain
2 Département de Recherches Spatiales, Observatoire Paris-Meudon, 92190 Meudon, France
3 Bureau des Longitudes, 77 Avenue Denfert Rochereau, 75014 Paris, France
4 Observatoire Pic-du-Midi, 65200 Bagnères-de-Bigorre, France

Ground-based observations of two conspicuous features near the north pole of Saturn, the polar vortex and the hexagonal wave structure, were made from July 1990 to October 1991, 10 years after their discovery. During this period the polar spot drifted in longitude, relative to system III, by –0.0353° per day on average. Superimposed on this mean motion, the spot also underwent short-term rapid excursions in longitude of up to sim14° at rates of up to sim1° per day. The spot also exhibited irregular variations in its latitude location. A combination of these data together with those obtained by Voyager 1 and 2 in 1980 and 1981 shows that the spot drifted –0.0577° per day for the 11-year interval from 1980 to 1991. The large lifetime of both features indicates that they are insensitive to the strong variations in the seasonal heating of the cloud layers in the upper polar atmosphere.

Submitted on November 30, 1992
Accepted on February 9, 1993


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Temperature and Composition of Saturn's Polar Hot Spots and Hexagon.
L. N. Fletcher, P. G. J. Irwin, G. S. Orton, N. A. Teanby, R. K. Achterberg, G. L. Bjoraker, P. L. Read, A. A. Simon-Miller, C. Howett, R. de Kok, et al. (2008)
Science 319, 79-81
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