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. Astronomy for students and general readers . mbered that there is an almost infinitevariety of such shapes. The figure by Sir John Herschbl on the next page gives a goodidea of a spiral or ring nebula. It has a central nucleus and a smalland bright companion nebula near it. In a larger telescope thanHerschels its aspect is even more complicated. See also Fig. 138. 460 ASTBONOMT. The Omega or Jvorseshoe nebula, so called from the resemblanceof the brightest end of it to a Greek S2, or to a horses iron shoe, isone of the most complex and remarkable of the nebulae visible inthe northern hemisph
. Astronomy for students and general readers . mbered that there is an almost infinitevariety of such shapes. The figure by Sir John Herschbl on the next page gives a goodidea of a spiral or ring nebula. It has a central nucleus and a smalland bright companion nebula near it. In a larger telescope thanHerschels its aspect is even more complicated. See also Fig. 138. 460 ASTBONOMT. The Omega or Jvorseshoe nebula, so called from the resemblanceof the brightest end of it to a Greek S2, or to a horses iron shoe, isone of the most complex and remarkable of the nebulae visible inthe northern hemisphere. It is particularly worthy of note, asthere is some reason to believe that it has a proper motion. Cer-tain, it is that the bright star which in the figure is at the left-handTipper corner of one of the squares, and on the left-hand (west)edge of the streak of nebulosity, was in the older drawings placedon the other side of this streak, or within the dark bay, thus mak-ing it at least probable that either the star or the nebula has Fig. 125.—spiral nebula. The trifid nebula, so called on account of its three brancheswhich meet near a central dark space, is a striking object, andwas suspected by Sir John Hekschbl to have a proper observations seem to confirm this, and in particular the threebright stars on the left-hand edge of the right-hand (east) mass arenow more deeply immersed in the nebula than they were observedto be by Hersohel (1833) and Mason, of Tale College (1837). In1784, Sir William Hersohel described them as in the middle ofthe [dark] triangle. This description does not apply to theirpresent situation. (Fig. 127).
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Keywords: ., bookcentury1800, bookdecade1880, bookpublis, booksubjectastronomy