Newcomb, Simon, 1835-1909, Holden, Edward Singleton, 1846-1914, joint author · New York, H. Holt · leaf 308
weeks, or months. But so long as they lastthey move regularly from east to west on the suns appar-ent disk, making one complete rotation in about 25 days.This period of 25 days is therefore approximately the rota-tion period of the sun itself. Spotted Region.—It is found that the spots are chiefly… … Fig. 79.—photograph op the sun. more rare than in latitudes 10° north or south. Connected -withthe spots, but lying on or above the solar surface, are faculce, mot-tlings of light brighter than the general surface of the sun. Theformation of a sun-spot is said to be often presaged by the…
Astronomy
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
![An illustration from Novae coelestium terrestriumq[ue] rerum observationes : et fortasse hactenus non uulgatae (1646)](https://img.insideoutlibrary.com/img/200/ia-novaecoelestiumt00font-48-15.webp)
