Show illimitable DISTANCE it tabes takes 1 yeara years for the light of some mars to beach reach Us while however it la Is interesting to know the distance of some of the stars in miles when stated in that way the numbers are so large that they tre fre convey very indistinct concep tion to the mind for this reason it Is customary to estimate star distances in light years A light year la is the dis tance that light moi ing at the rate of 0 miles per second travels in one year this amounts in round numbers to 5 miles the distance of alpha Cent aurl Is 4 35 light years that of sirius the dog star Is almost exactly twice as great or 8 86 6 light years in other words light requires 8 6 years to come to us from sirius and these are among the very nearest of the stars some whose parallaxes have been rather estimated than measured appear to be situated at a distance which light could not traverse in less than one or two centuries the great star arcturus Arc turns for instance has accord ing to dr elkin a parallax of only eighteen one thousandths of a second its distance must in th it tt case be about light years or mor than 1 miles and if its distance Is so great then since light varies inversely as the square of the distance from its source it can be shown that arcturus Arc turns must actually give 5 or 6 times as much light as the sun yields yet arcturus Arc turns Is evidently much nearer than the vast majority of the stars are not one in a million Is known to have a parallax large enough even to be intelligently guessed at there may be stars whose light requires thou sands instead of hundreds of years to cross the space separating them from us we thus see that only a few points on the nearer shores of the starry universe lie within reach of our measure ments here and there a jutting head land while behind stretches the vast expanse over which the hundras of millions of stars known to exist are scat seat |