Astronomy for amateurs . Fig. 36.—The Evening Star. feel some curiosity about the mysteries of the brutalities of daily life would fain petrify our dreams,but thought is not yet stifled to the point of checking all 123 ASTRONOMY FOR AMATEURS aspirations after eternal truth, and when we gaze at thestarry sky it is hard not to ask ourselves the nature ofthose other worlds, and the place occupied by our ownplanet in the vast concert of sidereal harmony. Even through a small telescope, Venus offers re-markable phases. Fig. 37 gives some notion of the succession of these,and of the pla
Astronomy for amateurs . Fig. 36.—The Evening Star. feel some curiosity about the mysteries of the brutalities of daily life would fain petrify our dreams,but thought is not yet stifled to the point of checking all 123 ASTRONOMY FOR AMATEURS aspirations after eternal truth, and when we gaze at thestarry sky it is hard not to ask ourselves the nature ofthose other worlds, and the place occupied by our ownplanet in the vast concert of sidereal harmony. Even through a small telescope, Venus offers re-markable phases. Fig. 37 gives some notion of the succession of these,and of the planets variations in magnitude during its. Fig. 37.—Successive phases of Venus. journey round the Sun. Imagine it to be rotating in ayear of 224 days, 16 hours, 49 minutes, 8 seconds at adistance of 108 million kilometers (67,000,000 miles),the Earth being at 149 million (93,000,000 miles). LikeMercury, at certain periods it passes between the Sunand ourselves, and as its illuminated hemisphere is ofcourse turned toward the orb of day, we at those timesperceive only a sharp and very luminous crescent. At 124 THE PLANETS such periods Venus is entirely, so to say, against the Sun,and presents to us her greatest apparent dimension(Fig. 38). Sometimes, again, Hke Mercury, she passesimmediately in front of the Sun, forming a perfectlyround black spot; this happened on December 8, 1874,and December 6, 1882; and will recur on June 7, 2004,and June 5, 2012^ These transits have been utilized incelestial geometry in measuring the distance of the Sun. You will readily divine that the distance of Venusvaries considerably according to he
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