Occultations of Stars by Planets, Moons, and Rings

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Dr. James Elliot will use the observational technique of stellar occultations of Solar System objects to probe the characteristics of planets and their rings in the outer Solar System. The spatial resolution of this technique should be about 4 kilometers which is several thousand times better than is possible with ordinary Earth-based methods. In 1989 Dr. Elliot will observe an occultation of a bright star by Saturn and its rings. Saturn is expected to occult such a bright star once every 80 years, on average, so this upcoming event presents a unique opportunity to probe the ring system at high spatial resolution from Earth. These and subsequent observations should improve the kinematic model of Saturn's rings by a factor of 20 over what has been possible with data from the Voyager spacecraft. From these data should come answers to fundamental questions about the structure and time scales of evolution of the ring system of Saturn. The occultation studies also include investigation of the upper atmospheres of Saturn and Uranus, since the technique can produce temperature, pressure, and number density profiles at high spatial resolution.