A CELESTIAL VISITOR

Hokitika Guardian, 18 December 1930, Page 2

A CELESTIAL VISITOR

Reception' committees of astronomers already are preparing for what will probably be the chief astronomical event of 1931; the visit of the asteroid named Eros, a tiny planet probably only fifteen or twenty miles in diameter, but' which has the unique distinction of being the celestial object which comes nearest to the earth, excepting only the meteors, an oeoas■ionnl comet- and our continual companion the .moon: It is possible theoretically for Bros to come within fourteen million , miles of the earth, not much over a third of the minimum distance of Mars, This closest ap-, proac-h depends, however, upon both planets being in exactly , the right places in their orbits at- the same in- 1 stant, arid that will, not happen this 'year. The earth will be a. trifle late for a perfect rendezvous,cnd the nearest distance of the two -bodies, on January 30, 1931,-: will be : about 18,200,000 miles.; Aside from the interest of entertaining the nearest vistior which has approached us since the rise of modern astronomy, the visit of Eros offers two opportunities- of some- importance, It is expected to provide more accurate measures than are now available of the distance between- the earth, and the sun, and of the weisht of the moon. It; is easy to calculate relative dis-; tances in the solar system from the laws of moving, bodies and from observations of the planets, To reduce these relative measures to terms of. miles one needs at least- one mile-measure from which tp evaluate the rest. This is what Eros will orovide. Its distance from the earth ' in' miles will be meoc. ured by observing the -angles which, it makes at the same instant from different earthly observatories, on the same principle as' the range finder used on battleships to measure the distance of an enemy by the angles of observation at • the two ends of a telescopic tube. \yiiite this distance measurement is being' made other observations wall trace the slight- wobbles of Eros in its calculated orbit and .from these methematieians will compute the weights of earth..! gravitational attractions, . for these irregularities. Evert at its nearest it is unlikely that anyone will he able to see Eros with the; naked eve, but it mill be visible easily through even a small telescope. . —H;T. in the .Auckland Star. •