This nebula was not in itself hot, but as it rotated it contracted.
Such were a few of the theorems to which his discovery of this nebula led him.
The star ι (double as shown in Plate 3) below the nebula is involved in a strong nebulosity.
Nebulosa means cloudy or dark, from nebula, a cloud; from its color.
That this was a phenomenon connected with the nebula is most probable, but just what occurred to produce it nobody knows.
The starting-point, the nebula, is no figment of the scientific imagination.
Adjacent to this nebula is another of the same class with a double nucleus, and associated with it is a nebulous star.
The stars were almost gone, the center of the nebula only a faint wisp.
It is small but well-defined, so that it looks more like a flat oval solid ring than a nebula.
What, then, is the origin of a nebula, and what the physical explanation of that origin?
early 15c., nebule "a cloud, mist," from Latin nebula "mist, vapor, fog, smoke, exhalation," figuratively "darkness, obscurity," from PIE *nebh- "cloud" (cf. Sanskrit nabhas- "vapor, cloud, mists, fog, sky;" Greek nephele, nephos "cloud;" German nebel "fog;" Old English nifol "dark, gloomy;" Welsh niwl "cloud, fog;" Slavic nebo).
Re-borrowed from Latin 1660s in sense of "cataracts in the eye;" astronomical meaning "cloud-like patch in the night sky" first recorded c.1730. As early as Hershel (1802) astronomers realized that some nebulae were star clusters, but certain distinction of relatively nearby cosmic gas clouds from distant galaxies was not made until 1920s, using the new 100-inch Mt. Wilson telescope.
nebula neb·u·la (něb'yə-lə)
n. pl. neb·u·las or neb·u·lae (-lē')
A faint, foglike opacity of the cornea.
A class of oily preparations for use in a nebulizer.
Plural nebulae (něb'yə-lē') or nebulas
A visible, thinly spread cloud of interstellar gas and dust. Some nebulae are the remnants of a supernova explosion, others are gravity-induced condensations of the gases in the interstellar medium which in certain cases may become a site for the formation of new stars. The term was formerly used of any hazy, seemingly cloudlike object, including what are now recognized as other galaxies beyond the Milky Way; it is restricted now to actual clouds of gas and dust within our own galaxy. ◇ Nebulae are generally classified as bright or dark. Among the bright nebulae are cold clouds that reflect light from nearby stars (reflection nebulae) and hot, ionized clouds that glow with their own light (emission nebulae). Dark nebulae—cold clouds that absorb the passing light from background stars—are called absorption nebulae. See more at star.