dipper@utastro.UUCP (Debbie Byrd) (09/24/85)
Uranus may have been pushed over on its side by a huge body flying loose in the early solar system. More -- after this. September 24 Four Months to Uranus Uranus -- the seventh planet out from the sun -- is now just four months away from its history-making encounter with the Voyager 2 spacecraft. Voyager will be closest to Uranus on January 24, 1986. Uranus has thin rings -- and five known moons. It's the third largest known system of worlds, after Jupiter, Saturn, and their rings and moons. The orbits of the uranian moons are very regular. They're practically circular, and all but one of the moons orbits almost directly above the planet's equator. But it's strange that their orbits are so regular -- because the entire uranian system is tipped over sideways with respect to the plane of the solar system. It's thought that Uranus may have been hit in the days of the early solar system by a large chunk left over from the formation of the planets. The impact may have pushed Uranus and its icy moons over sideways. It may even have helped form the moons. Two of the moons of Uranus -- Ariel and Miranda -- reflect more sunlight than their companions. Theory suggests they may be covered with deposits of fresh ice. There may have been volcanos spewing ice onto the surfaces of these moons in the relatively recent past. Voyager may capture images of volcanic ice flows -- or even ice volcanos in eruption -- when it passes within 20 thousand miles of Miranda and 80 thousand miles of Ariel. Again, Voyager's closest approach to Uranus is January 24, 1986 -- just four months from today. Script by Deborah Byrd. (c) Copyright 1984, 1985 McDonald Observatory, University of Texas at Austin