Page images
PDF
EPUB

corona

was

the moon, by noting the exact times of About once every two years a total contact of the limbs of the sun and eclipse may be seen somewhere on the moon. The beautiful

earth's surface, but as some of these watched with awe and admiration, and eclipse tracks lie almost wholly on the a few sketches were made of its form, water surface of the earth, or fall upon

- but there the study of an eclipse inaccessible portions of the globe, it is ended. In fact, an eclipse was watched only on an average of about once in only if the shadow happened to cross three years that a total eclipse falls at the observer. So little interest was a habitable spot on the earth, even taken in the phenomena, so few inves- though that location, as in 1901, may tigations were planned, that no expe- be so far away. On the average a total ditions were sent out.

eclipse lasts for about two minutes, so How different is the scientific atti- that in a century, about sixty minutes, tude in the twentieth century! In the or one short hour of time, is given to year 1901, the writer of this article the astronomer for his investigations. traveled halfway round the world to the Yet in spite of the brevity of time far-off Dutch East Indies in order to ob- afforded, some very startling results serve the total eclipse of May 18 of that have been accumulated ! year. In other words, he went as far As is well known, an eclipse takes from home as it was possible to go, and place when the sun, earth, and moon the purpose of this trip was to make are in a straight line, an eclipse of the observations which were concentrated sun occurring when the moon comes within the time of six short minutes. between the sun and the earth, or when

The writer regards himself as very the earth passes into the shadow cast fortunate in having been selected four by the moon. The earth makes an antimes to become a member of the party nual journey about the sun, traveling of the United States Naval Observa- in the ecliptic at the speed of more than tory, and he has thus seen the eclipses eighteen miles a second, and accomof 1900, 1901, 1905, 1918, and alto- plishing its journey in 36514 days. The gether has traveled about 10,000 miles

distance from the sun is on the average for this purpose.

of ninety-three millions of miles, but As a matter of fact, an eclipse is not the earth's orbit is not a circle but an of the rare occurrence that the fore- ellipse, so that the distance from sun going remarks might lead one to be- to earth may vary. one and a half millieve. Each and every year there must

lion miles on either side of the mean. be two eclipses of the sun, and there Once a month, the moon revolves about may be even more. Somewhere on the the earth, but it likewise does not move earth each year two eclipses of the sun in a circle so that the distance from may be observed, but usually these earth to moon varies considerably on eclipses are partial eclipses, the sun either side of the average of 239,000 being only partly obscured. Since few miles. Moreover, the moon's path is not scientific facts can be learned at a par- exactly in the plane of the ecliptic, but tial eclipse, the astronomer takes little is inclined to the ecliptic by a small interest in them. It is only when the amount, a little more than five degrees sun's surface is wholly covered up that of angle. An eclipse of the sun can the matchless corona may be seen; it is take place only at the time of new only at the time of a total eclipse that moon, so that manifestly it is only at there is furnished the unusual oppor- the time of new moon, when in addition tunity of investigating the sun's sur- the moon is near the plane of the ecliproundings when the brilliant glare of tic, that an eclipse of the sun can take the sun itself is absent.

place.

[ocr errors]

THE TOTAL SOLAR ECLIPSE OF 1918

247

Although the average motions of the the globe for the purpose of making moon have for some time been so well observations. Thus in 1901, in farknown that the general time and loca- distant Sumatra, in addition to a large tions of eclipses may be predicted at party from the United States, there long range with a considerable degree were gathered astronomers from Engof accuracy, still it may be truthfullyland, France, Germany, Holland, and said that the moon has given the mathe- Japan.

Japan. For the eclipse of 1905, which matical astronomer more work and took place in Europe, there were conworry than all the millions of stars of gregated in the eclipse track, hundreds the universe, with the result that to of astronomers, professional and 'amapredict the time of coming of an teur, from every civilized nation of the eclipse at any one locality exactly to world. The trip in 1901 was a most the fraction of a second taxes the in- fascinating one, including as it did a genuity of the astronomer even today. journey across the continent to San It is no wonder, therefore, that man Francisco; from the Golden Gate to should always have regarded the moon Manila, stopping en route for three as of the feminine gender!

days at Honolulu; and ten or a dozen The distance and dimensions of the days' stay in Manila while waiting for sun and moon being known, it is com- the United States gunboat which took paratively easy to find out the diameter the party the remaining 2200 miles of the moon's shadow intercepted by the along the coast of Palawan and Borneo, earth. The maximum width of the across the equator, and through the shadow is 168 miles, and when all con- Strait of Sunda to the west coast of ditions are most favorable, the total the Island of Sumatra. A stay of eight eclipse may last for somewhat more weeks in the interior of the island was than seven minutes. Under average necessary in preparation for the eclipse, conditions, the region on the earth a site having been chosen at the termiwhere the total eclipse may be observed nus of the government railroad. The is less than one hundred miles in width, country was picturesque, the manners and the average duration of totality is and customs of the people most interabout two minutes of time. The chance esting, for, belonging as it does to the that the stay-at-home might see many Dutch, who have peculiar ideas of their total eclipses in his lifetime is very lim- own regarding colonization, few foreign ited. As a matter of fact, in London influences had been allowed to disturb before the eclipse of 1751, there had the primitive lives of the natives. Innot been a single total eclipse of the deed, ten miles due east of the eclipse sun visible for more than six centuries. camp so little is known of the country At anyone location, an inhabitant that it is said cannibals are still in would see many more total eclipses of existence there. the moon than of the sun. When the In 1905 there was another attractive moon passes into the shadow of the trip, when a voyage was made across earth and is eclipsed, then wherever the Atlantic aboard the U. S. S. “Minupon the earth's surface the moon is neapolis" which was the flagship of visible, the eclipse may also be seen. Rear Admiral Chester, then SuperinThe result is that each total eclipse of tendent of the United States Naval the moon is visible over more than half Observatory. At Gibraltar, we had the the earth, while on the other hand the pleasure of viewing the British Meditotal solar eclipse is visible only over terranean fleet with Admiral Lord a narrow track.

Beresford in command. Eclipse obOrdinarily a total solar eclipse at- servations were made from the little tracts astronomers from all quarters of town of Daroca in the interior of Spain

[graphic]

PATH OF THE TOTAL ECLIPSE OF THE SUN, JUNE 8,

1918

[ocr errors]
[ocr errors]

The sun could be seen totally eclipsed only in the area bounded by the two close parallel lines, which is about sixty miles wide. Outside of this area the sun was partly eclipsed. At sunrise the eclipse began in the Pacific Ocean off the coast of China and Japan. The shadow traveled across the Pacific at the rate of more than a thousand miles an hour so that it reached the United States well after noon. It is notable that with the exception of a few small islands the only land touched by the moon's shadow was the American Continent

[ocr errors]
[ocr errors]
[ocr errors]
[ocr errors]
[graphic]
[ocr errors]
[ocr errors]
[ocr errors]
[ocr errors]
[ocr errors]
[ocr errors]
[ocr errors]
[ocr errors]
[ocr errors]

150°

ENGRAVED AND PRINTED BY THE US.GEOLOGICAL SURVEY

[graphic][graphic]

FOOTHILLS OF THE ELKHORN RANGE BEHIND THE CITY OF BAKER (UPPER PICTURE)

The city of Baker obtains its water supply from the melting snows of the Elkhorn Range (the pipe line comes over the hills at the point indicated by the arrow). On the day of the eclipse the citizens of Baker repaired to these foothills, from which they could obtain a fine view of the range and the valley, to watch for the shadow of the moon, which rushed across the landscape at the instant of totality with the great speed of about thirty miles a minute

« PreviousContinue »