Astronomy for the use of schools and academies (1882)
Gillet, J. A. (Joseph Anthony), 1837-1908, Rolfe, W. J. (William James), 1827-1910 · New York : Potter, Ainsworth, & Co. · leaf 328
isappearing. Three or four such shooting-starsmay, on the average, be observed in the course of an hour.They are usually seen only a second or two • but they some-times move slowly, and are visible much longer. Thesestars begin to be visible at an average height of aboutseventy-five miles, and they… … Fig. 340. vary from ten to a hundred miles in length, though theyare occasionally two hundred or three hundred miles long.Their average velocity, relatively to the earths surface, variesfrom ten to forty-five miles a second. The average number of shooting-stars visible to thenaked eye at any one…
Astronomy
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