Show heavenly distances are al e measured by L light ight speed celestial phenomena ar arouse ouse interest of laymen washington D C total eclipses unusual sunspot sun spot activity radio fadeouts fad eouts and other celestial phenomena breaking into news columns these days make necessary a yardstick by which the layman can straighten out his conceptions of heavenly distances says the national geographic society the two facto factors rs in important eclipses the moon and sun may seem impressively far away when their distances are measured in miles but they are really very close in terms of the time required for their light to reach the earth arth e the moon our nearest neighbor in space is roughly miles from the surface of the earth facing it it is a dead world and gives out no light of its own but its reflected light from the sun travels through space at the same speed as direct sunlight approximately miles a second light therefore reaches us from the moon in about ivi minutes almost a negligible P period briod of time the suns mean distance from the earth is much more impressive in miles approximately but light from the sun piercing space at its tremendous speed reaches the earth in a mere matter of df minutes our temperature and other weather phenomena and even life itself are dependent on the continued flow of light from the sun and since the light stream travels to us so swiftly it results that effects on earth are tied extremely closely to events on the sun sun storms affect radio with radio communication as widely developed as it is today there are striking demonstrations of the effective closeness of the sun to the earth scientists recently photographed the flaring up of a brilliant spot of light on an the sun recorded the time and found that at the same instant radio signals of certain frequencies faded out completely the earths fellow planets of the solar system are also close clos by venus which approaches nearer to the earth than any heavenly body e except capt the moon is only miles away at the closest and light then reflected from it reaches the earth in 2 minutes neptune farthest of the major planets is 2 billion miles away at its closest approach and sight light then reflected from it reaches the earth in about four hours these and the other members of our own solar system are the earths only neighbors when we consider heavenly bodies outside the suns family the so called fixed stars we run into stupendous depths of empty space before finding the nearest star in measuring such distances as this miles become meaningless instead there is brought into use as a measuring unit the vast I 1 light flight year this is the distance that light rushing through space at miles a second travels in one year or more than million seconds in miles a light year is more than times one billion a figure far too cumbersome to use especially when it is multiplied many times as it must be in measuring the distances to the more remote stars astronomers have therefore saved both time and mental wear and tear by inventing the light year incredible distances the nearest star to the earth is proxima pronima visible from the southern hemisphere which is light years away numerous stars have hav been observed which are as much k as light years distant far beyond these are the great nebulae vast groups of stars or island universes the nearest of them are estimated to be light years away and the farthest faintly visible in the worlds or I 1 ds largest larges t telescope are estimated to be the almost unthinkable and incredible distance of million light years away from the earth it is when we deal with distant fixed stars and nebulae very far outside our solar system that we run into the fascinating and romantic fact that the star which we see at any moment is not the star as it now exists but the star as it was five hundred a thousand or several million years ago thus if we were to look tonight through a telescope at the star rigel we would see its light which started from the star years ago some ten years before christopher columbus was born even it if rigel had been blot ted out of existence years ago it would continue to the observer from the earth to shine irr in its accustomed cus tomed place in the heavens for years yet to come |