Rings appear to be circling the remote planet Uranus, a finding that would make it the second planet in the solar system to have rings around it.
The discovery of what scientists believe are rings around Uranus means the magnificent rings of Saturn are no longer unique to the solar system of nine planets, a supposition treated as scientific fact since 1035 when dutch astronomer Christian Huygens identified Saturn's rings for the first time.
At no [WORD ILLEGIBLE] IN THE LAST 320 YEARS had astronomers been able to locate a second planet with rings, because the light of the more remote planets like Uranus washes out anything else close to the planets and because the right conditions and instruments are only now available to observe details close to planets farther out than Saturn.
In what some astronomers described as a major breakthrough, three scientists from Cornell University found and observatories in Australia and India confirmed what the three say are rings of rock and ice around the equatorial belt of Uranus, the seventh planet out from the sun and 1.7 billion miles from earth.
So important is the finding that the Smithsonian Astronomical Observatory in Cambridge, Mass., sent telegrams yesterday to astronomers around the world suggesting where and how they look to duplicate the discovery. The Cornell team was as surprised by the discovery as everybody else in the astronomical community.
"We weren't looking for rings at all," said Cornell's Dr. James Elliott, leader of the team that included Drs. Edward Dunham and Douglas Mink. "What we were looking into was the atmospheric properties of the planet itself, to see if we could read its composition and temperature."
Flying in the space agency's C-141 "Airborne Observatory" east of Australia on March 10, the Cornell astronomers aimed the aircraft's 36-inch telescope at Uranus, which on that night was passing in front of a distant star in the Constellation Libra that does not have a name. Its catalogue number is SAO-158687, the SAO standing for Smithsonian Astronimical Observatory.
In the nine minutes before Uranus completely blocked out the star's light and in the nine minutes after, the telescope lost sight of the star for periods of about eight seconds at 10 different times. Five times it lost the star before the planet blocked it out and five times it lost the star after the star emerged on the other side of the planet.
Uranus has five known moons, none of which could have caused the 10 blackouts.The moon closest to the planet lies about 160,000 miles out from the planet and the blackouts took place about 27,000 miles from the planet on either side of the planet.
"I think we were looking through a very faint ring system similar to the rings of Saturn," Elliott said yesterday from his office at Cornell. "The fact that there were five blackouts on either side of the planet suggests rings and not moons, since moons would have been placed around the planet in a more random way."
Elliott's discovery was confirmed by the University of Arizona's Robert Millis, who observed the same phenomenon on one side of the planet using an observatory near Perth in Australia. The Smithsonian observatory said an Indian astronomer saw the same thing with a telescope outside New Delhi.
Neither one saw blackouts on the far side of Uranus because dawn was obscuring the planet. Elliott's aircraft was still in the dark.
Harvard University's Dr. Alastair Cameron said it was possible that all planets had rings when they were formed 4.6 billion years ago but that the sun evaporated the rings of the innermost planets over time. The rings of Saturn have been found to be made of ice.