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No. 40: Jul-Aug 1985

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Next Let Us Consider Uranus

Uranus is so distant that its satellites are difficult to observe. What astronomers do see is unsettling. The orbital eccentricities of the three inner satellites, using reasonable assumptions about tidal interactions, should decay to zero (perfect circles) in 107 -108 years. If the observational data are correct, one implication is that the Uranian satellite system should be evolving rapidly from a state of higher eccentricity.

(Squyres. Steven W., et al; "The Enigma of the Uranian Satellites' Orbital Eccentricities," Icarus, 61:218, 1985.)

Comment. Here we have one more sign of recent disturbance or solar-system youth. Time spans of 107 -108 years are very small compared to the estimated solar-system age of 5 x 109 years.

From Science Frontiers #40, JUL-AUG 1985. 1985-2000 William R. Corliss