TRAIL OF DARKNESS

Sun (Auckland), Volume III, Issue 658, 9 May 1929, Page 9

TRAIL OF DARKNESS

ECLIPSE TRACES PATH OF SHADOW OVER EARTH SCIENTISTS KEEP WATCH More than eight scientific expeditions, each with many thousands of pounds worth of scientific instruments, are today scattered along a band 100 miles wide, stretching in a wide curve from a point in the Indian Ocean n:*r Madagascar to the Philippine Islands, over which an eclipse of the sun is now casting a trail of darkness. 'J'HE eclipse, thanks to the fact. that totality at each point lasts for something like six minutes, is one of the most important for many years past and for many 3*ears to com e. Six minutes, though only a short time, is nearly the maximum period thai any eclipse can last. and. since ttaerp are many important phenomena that can only be observed during an eclipse, every second is of inestimable value to astronomers. The expeditions which are now engaged in the work are ranged along the line that the period of darkness will take, w'hich passes over the Indian Ocean. Sumatra, Cochin China. Siam, the Malay Peninsula and finally tbe Philippine Islands. The two United States expeditions have their headquarters at Iloilo, south of Manila in the Philippines. The two British parties are on a small island just, south of the Malay Peninsula and others are working from an island to the north of Sumatra.

The eclipse is, of course, caused by the moon’s passage between the earth and the sun. The moon is considerably smaller than the sun so that a cone-shaped shadow is thrown, the tip of which just reaches the earth’s surface. As the earth revolves this shadow’ traces out a broad curve which swings over nearly half the world. During this eclipse, which, it is interesting to note, is the third to pass over Sumatra in this huge cameras will photograph the sun during every second of darkness. From these photographs and from individual observation, studies of the sun's corona and of the prominences on its surface will be made. The prominences are huge flame-like structures which apparently rush out from the sun’s surface at hundreds of miles a second for distances of thousands of miles. The corona, about which comaparatively little is known, is a diffused light that is so weak as to he only visible when the main glare of the sun is hidden in shadow. Not the least interesting subject for investigation is the Einstein theory of the effect of gravitation on light. It is hoped that it will be defintely proved that “light,” to quote a London newspaper, may be “caught bending.”

Those who were in England early last year may remember the eclipse that passed over the island then, and the weird lights and shadows thrown by tbe sun’s corona and prominences. It is said that tbe birds, believing it. to be night time, went to roost and that when the light returned roosters greeted it as the break of day. It is probable, too, that experiments are being carried out today to determine the effect of such an eclipse on radio communication. So far as is known at present, the effects observed are very similar to those of sunrise and sunset, but it. is doubtful if the subject has been fully investigated.