STAR LIGHT. AND HEAT

Evening Post, Volume CXVI, Issue 142, 13 December 1933, Page 4

STAR LIGHT. AND HEAT

It would take over 1,000,000,000,000 years for the heat the earth receives from the nearest star to boil a pint of water, provided that no heat received by the water was. lost by radiation. This heat, '• according to an American scientist, is v about equal to the heat one would feel v from a candle fifty-three miles away, and to measure it scientists use a thermocouple. To make a simple thermocouple','tho-ends of a wire of one metal are soldered to the ends of a wire of some other metal, thus making a circuit of wire with two joints. If one of these {joints is heated to a higher temperature than the other, an electric current passes along the wire and can be detected by a galvanometer. In tho thermocouple used to measure the heat of starshine, astronomers use bismuth for one metal and a mixture of bismuth and tin for the other. The light coming from a star is focused in a large telescope and allowed to fall upon one of the junctions of the thermocouple which is "blackened so. as to'absorb all the heat it receives. The heat is sufficient to set up a current which a very delicate galvanometer can detect and measure, but even to. obtain this result, the wire of the thermocouple must be as fine as hairs.