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No. 38: Mar-Apr 1985

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Neptune's incomplete ring

When the star SAO 186001 had a "close" encounter with Neptune on July 22, 1984, a number of astronomers were watching it carefully to see its light was diminished by an encircling, Saturn-like ring of particles surrounding Neptune. The ring system of Uranus was discovered by studies of similar stellar occultations. Sure enough, astronomers at the European Southern Observatory, in Chile, and the Cerro Tololo Observatory, also in Chile 90 kilometers away, detected a 1-second, 35% reduction in the star's light at the same instant. These data indicate the presence of an object 10-20 kilometers wide -- hardly an undicovered satellite, but possibly a ring. But given the geometry shown, there should have been two occultations, but only the one on the right was registered. Speculation is now rife that Neptune has a partial ring or a grotesquely twisted one.

(Eberhart, J.; "Signs of a Puzzling Ring around Neptune," Science News, 127:37, 1985.)

Comment. Of course the geometry of the ring could have been such that the star was tangent at one point. It should also be noted that modern astronomers have always laughed off the 1846-1847 observations of a Neptunian ring by W. Lassell and J. Challis!

From Science Frontiers #38, MAR-APR 1985. 1985-2000 William R. Corliss