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Session 116 - The Solar System.
Oral session, Thursday, January 18
Salon del Rey Central, Hilton
The powerful radio noise emitted sporadically by Jupiter at decameter wavelengths has been monitored regularly at the University of Florida Radio Observatory since 1957, and at Maipu Radio Astronomy Observatory in Chile from 1957 to 1977. The Florida database now consists of 35 years of coverage for rotation period determinations, and for the investigation of other long-term effects. Adding new data collected at several frequencies from 1980 to 1992, and using a proven technique for rotation period determinations, we calculated a new and considerably more precise magnetospheric rotation period for Jupiter. Our results indicate a period that is significantly different from the International Astronomical Union's accepted System III (1965) period. We also conclude that there is a drift toward shorter rotation periods, but the significance of this measurement is marginal. Earth is the only planet for which variability in the global magnetic field has been detected. This is the first evidence that the IAU System III (1965) rotation period may need revision.
