Show I halley's Comet Come On its last visit Halley's flaUey's comet was under observation by astronomer astron omen omer through their telescopes from September 1009 to July 1911 Abo About t Way 1910 1010 it was brightest and was wu then a conspicuous object to th the naked eye Its Us mean period is 77 years which would bring it U back in to 1987 However because of the gravitational gravitational grav gray attraction of planets which it passes passu Ii in its orbit an actual p pa t rind JUa nay may 1 be e as much as two and It a half haU years yean longer or oy shorter than the mean Probably no one as yet yit has calculated exactly what these planetary effects will be but this will be done sufficiently in iq advance to enable astronomers t to know knoN when and where to loo loot look for U 8 H. H around 1085 |