Lowell, Percival, 1855-1916 · New York, The Macmillan company · leaf 40
at Nebula in Andromeda — after Ritchey. neither irregular like the great nebula in Orion nor roundlike the so-called planetary nebulae,—the two greatclasses at that time known, — but exhibited a striking BIRTH OF A SOLAR SYSTEM 19 spiral structure. It proved the forerunner of a remark-able… … NeBULA M. 100 COM^ —■ AFTER ROBERTS. graphic means improved, the number of such objectsdetected steadily increased until about thirteen yearsago Keeler by his systematic discoveries of them cameto the conclusion that a spiral structure pervaded thegreat majority of all the nebulae visible. Their…
Cosmogony
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