ECLIPSE 



1915 



ECLIPSE 



not satisfied, and in 1520 he visited Rome and 

 urged the Pope to take measures against 

 Luther. The Pope assented and he returned 

 with the bull, or edict, of condemnation, which 

 Luther publicly burned. In 1527 Eck disputed 

 at Baden, Switzerland, with Haller of Berne 

 and attended the Augsburg Diet in 1530. He 

 also took part in the conference at Worms in 

 1540. See LUTHER, MARTIN. G.W.M. 



ECLIPSE, e klips', the total or partial ob- 

 scuring of a heavenly body by another or by 

 the shadow of another. This phenomenon is 

 called an eclipse -only when it affects the sun 

 or the moon. The hiding of one star by an- 

 other is called an occupation. A very simple 

 experiment clearly illustrates the phenomenon 

 of an eclipse. A small marble held between 

 the thumb and forefinger a short distance be- 

 fore one eye will completely hide the moon ; 

 at a greater distance it shows the effect of an 

 annular eclipse, by which is meant leaving a 

 ring of the moon visible. By moving it to 

 one side the appearance of a partial eclipse 

 may be obtained. The same results would be 

 noticed with regard to the sun, but that body 

 is too bright to be directly regarded by the 

 naked eye. 



Superstitions concerning the supernatural 

 causes of eclipses have not yet completely died 

 out. In Russia an eelipse is still believed by 

 the peasants to be a sign of the wrath of God. 

 In 1914, during the early stages of the War of 



..--:---'"' Moon 

 Fig. 2 



DIAGRAMS EXPLAINING ECLIPSES 



the Nations, an eclipse occurred, and a special 

 warning was issued explaining to the ignorant 

 Russian soldiers that it was not a sign that 

 God had doomed them to defeat. 



Eclipse of the Moon. Although long re- 

 garded as supernatural, an eclipse of the moon 

 is easily explained as the result of purely nat- 



ural causes. The light of the sun upon the 

 earth causes the earth to throw a shadow into 

 space. When the moon, in its journey round 

 the earth, enters that shadow it becomes ob- 

 scured. It may be totally or partially eclipsed, 

 but even when completely in the shadow of 

 the earth it remains visible, owing to the re- 

 fraction of the sun's light. The eclipse always 

 commences on the eastern side of the moon and 

 ends on the western. A total eclipse may 

 last two hours, as the shadow thrown by the 

 earth at the point where the moon enters it 

 is double the diameter of the moon, which 

 itself travels the length of its diameter in one 

 hour. Lunar eclipses happen only when the 

 moon is at the full. They do not happen at 

 every full moon, as the moon generally passes 

 the shadow without entering it. The accom- 

 panying diagram shows the conelike nature of 

 the shadow thrown by the spherical body of 

 the earth (see Fig. 1). It completely eclipses 

 the moon to those on the side of the earth 

 directly opposite the sun. 



Eclipse of the Sun. When the moon passes 

 between the earth and the sun it hides the 

 face of the sun, partially or completely. It 

 may pass so near to the earth that the face 

 of the sun is fully covered, or it may pass 

 across the sun so that only part of that orb is 

 concealed. What is termed an annular eclipse 

 may be produced by the passage of the moon 

 at such a distance from the earth that it ob- 

 scures only the central portion of the sun's 

 disk, leaving an outer ring visible. An eclipse 

 of the sun commences on the eastern and ter- 

 minates on the western side. The accompany- 

 ing diagram (Fig. 2) explains the cauae of a 

 solar eclipse. The moon, being between the 

 sun and the earth, throws its direct shadow 

 on the earth at b, and to anyone on the 

 earth at this point the eclipse would be total. 

 The outer shadow between the tnie shadow 

 and the full outside light falls on the earth 

 between 6 and a and 6 and c. To persons on 

 the earth between these points the BUD would 

 be partially eclipsed. 



Predicting Eclipses. To the general observer 

 it appears little short of miraculous that 

 eclipses can be accurately predicted, but to the 

 astronomer, with the resources of spherical 

 trigonometry at his command, it is a compara- 

 tively simple matter. It does seem almost 

 incredible, however, that the ancients, who 



,.,, .1 almost n<. accurate scicntil b I - 



edge as to the movements of the heavenly 

 bodies, should have been able to foretell 



