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Io's triaxial figure.Timings from photoelectric observations of four immersions and two emersions of the recent occultation of Beta Scorpii C by Io have made it possible to derive Io's apparent equatorial radius to an accuracy of 2 km. However, when the distortion of Io attributable to rotation and tides raised by Jupiter is considered, the derived mean radius becomes several kilometers less than the observed equatorial radius. If Io were a homogeneous fluid body in hydrostatic equilibrium and in synchronous rotation, it would show a bulge along a line to Jupiter about 20 km in radius greater than the polar radius. The mean radius thus derived is (1818 plus or minus 5) km and mean density (2.88 plus or minus 0.34) g/cu cm, the largest uncertainty being attributable to the value of Io's mass. The new value for Io's radius is higher than those previously determined and suggests about 30% lower values for mean densities of all Galilean satellites.
Document ID
19720061035
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
O'Leary, B.
(San Francisco State College, San Francisco; NASA, Ames Research Center Moffett Field, Calif., United States)
Van Flandern, T. C.
(U.S. Naval Observatory Washington, D.C., United States)
Date Acquired
August 6, 2013
Publication Date
August 1, 1972
Publication Information
Publication: Icarus
Volume: 17
Subject Category
Space Sciences
Accession Number
72A44701
Funding Number(s)
CONTRACT_GRANT: NGR-05-036-104
Distribution Limits
Public
Copyright
Other

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