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Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: CHAPTER VII. DOUBLE STARS. We have hitherto been considering the stars as isolated points of light dotted hither and thither all over the heavens and as if they had no connection one with another. These suppositions are only true in a qualified Fig. 5.?a Herculis (double star). sense, for the telescope reveals the fact that no inconsid, erable number of the stars which we regard as simple points of light are in reality 2 (or in some cases several) single stars which are so close together as to ar the naked eye to be one. The proximity of one star to another might in any given case only be an effect of perspective and not an actual fact. For instance, a man standing on the top of a straight road which led up a hill might see 2 men approaching him, seemingly walking shoulder to shoulder, as if they were 2 friends engrossed in conversation, whereas in reality they might be isolated individuals walking up the hill, each on his own account, perhaps 50 yards apart. On the other hand, if the man at the top saw the other 2 men cross from one side of the road to the other simultaneously, and that as one turned his head askew, apparently to look at some distant object, the other did the same thing, he might justly infer that the two were really friends and were really walking side by side. The foregoing illustrations will define with perfect accuracy the difference between what is called an optical double-star (that is, 2 stars which seem to be linked together because of the effect of perspective) and a binary double-star; that is, 2 stars which not only seem to be linked together but truly are so. These last-named are often spoken of as physical doubles, or 2 stars physically connected. To determine in any given case whether a pair of stars belong to the one cl...
| ISBN-13 | 9781458937490 |
|---|---|
| ISBN-10 | 1458937496 |
| Weight | 0.25 Pounds |
| Dimensions | 9.00 x 6.00 x 0.16 In |
| List Price | $14.14 |
| Format | Paperback |
|---|---|
| Pages | 66 pages |
| Publisher | |
| Published On | 2009-08-01 |
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