Word: orbiting
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Dates: during 1980-1989
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...hunting for an agent that could explain the apparent clockwork regularity of the celestial barrages. Some suggest that a companion star to the sun periodically comes close enough to nudge comets gravitationally out of their natural habitat--a cloud of comets that circles the sun far beyond the orbit of Pluto--sending them hurtling toward earth. Others assign that role to Planet X, while some insist that the slow, bobbing ride of the sun and its planets around the Milky Way galaxy is responsible. Whatever the details, declares Paleontologist J. John Sepkoski Jr. of the University of Chicago, the evidence...
...break in 1983, Muller and fellow Astronomers Marc Davis of Berkeley and Piet Hut of the Institute for Advanced Study in Princeton were brainstorming about stars and periodicity, when Muller noted that more than half the stars in the galaxy are thought to be binaries (pairs of stars that orbit a common center of gravity). Suppose the sun has a companion, he mused, and that companion was somehow disrupting the solar system's asteroid belt. Trouble was, he conceded, he could not come up with a convincing orbit for the companion. Suddenly the Dutch-born Hut interrupted him with...
...three realized that the sun's counterpart, if it existed, would have to be like no other companion star ever identified; it would travel in an enormous elliptical orbit three light-years across that would periodically take it farther from the sun than the distance between any known binary stars. Because it has not been identified in the four centuries since astronomers began using telescopes, it must be very small and dim, perhaps a red dwarf with one-third the mass and only one one-thousandth the brilliance of the sun. When it passed through the Oort cloud, it would...
Reviews for the Nemesis debut were what might be called mixed. Critics charged that so gigantic an orbit had never been recorded for two companion stars, and with good reason. If the sun and its presumed partner were actually three light-years (18 trillion miles) apart, they said, the gravitational attraction between them would be so feeble that a passing star or dust cloud would have bumped Nemesis out of orbit long ago, certainly before it could come back through the Oort cloud a dozen times. Says Shoemaker, who has been something of an impartial judge in the periodicity controversy...
...tenth planet is somewhere out there. Astronomer Robert Harrington of the U.S. Naval Observatory has gone so far as to paint a description of the suspect, and it is no pedestrian planet. It is three to five times the mass of the earth, is gaseous like Jupiter, has an orbit that is elliptical rather than circular and inclines to the plane of the solar system at an angle of perhaps 30 degrees or more; its year (the time it takes to orbit the sun once) is 800 to 1,000 earth years long. To have been influential in shaping...