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 128
reciable density at themoon. (2) The absence of anatmosphere from the moonis also shown by the ab-sence of twilight and ofdiffused daylight. Upon the earth, twilightcontinues until the sun iseighteen degrees below thehorizon ; that is, day andnight are separated by abelt twelve hundred miles in… … Fig. 128. 112 ASTRONOMY. phere, we should notice a similar gradual transition fronthe bright to the dark portions of her surface. Such, how-ever, is not the case. The boundary between the light anddarkness, though irregular, is sharply defined. Close to thisboundary the unillumined portion of the…
Astronomy
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![An illustration from Sidereus nuncius : magna, longeque admirabilia spectacula pandens, suspiciendaque proponens vnicuique, praesertim verò philosophis, atq[ue] astronomis, quae à Galileo Galileo ... perspicilli nuper à se reperti beneficio sunt obseruata in lunae facie, fixis innumeris, lacteo circulo, stellis nebulosis, apprime verò in quatuor planetis circa Iouis stellam disparibus interuallis, atque periodis, celeritate mirabili circumuolutis; quos, nemini in hanc vsque diem cognitos, nouissimè author depraehendit primus; atque Medicea sidera nuncupandos decreuit (1610)](https://img.insideoutlibrary.com/img/200/ia-sidereusnunciusm00gali-25-9.webp)
