Astronomy for amateurs . mblem of inviolablepurity t To find any defect in him were to do himgrievous injury. Since the orb of day was incorruptible,those who threw doubt on his immaculate splendor werefools and idiots. And so when Scheiner, one of thefirst who studied the solar spots with the telescope,published the result of his experiments in i6lo, no one^ would believe his statements. Yet, from the observations of Galileo and otherastronomers, it became necessary to accept the evidence,and stranger still to recognize that it is by these veryspots that we are enabled to study the physical c
Astronomy for amateurs . mblem of inviolablepurity t To find any defect in him were to do himgrievous injury. Since the orb of day was incorruptible,those who threw doubt on his immaculate splendor werefools and idiots. And so when Scheiner, one of thefirst who studied the solar spots with the telescope,published the result of his experiments in i6lo, no one^ would believe his statements. Yet, from the observations of Galileo and otherastronomers, it became necessary to accept the evidence,and stranger still to recognize that it is by these veryspots that we are enabled to study the physical consti-tution of the Sun. They are generally rounded or oval in shape, andexhibit two distinct parts; first, the central portion, whichis black, and is called the nucleus^ or umbra; second, 95 ASTRONOMY FOR AMATEURS a clearer region, half shaded, which has received thename of penumbra. These parts are sharply definedin outline; the penumbra is gray, the nucleus looksblack in relation to the dazzling briUiancy of the solar. Fig. 29.—Direct photograph of the Sun. surface; but as a matter of fact it radiates a light 2,000times superior in intensity to that of the full moon. Some idea of the aspect of these spots may be ob-tained from the accompanying reproduction of a photo-graph of the Sun (taken September 8, 1898, at the 96 OUR STAR THE SUN authors observatory at Juvisy), and from the detaileddrawing of the large spot that broke out some dayslater (September 13), crossed by a bridge, and furrowed
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectastronomy, bookyear19
