Nebulous Nomenclature

An excercise in recreational etymology

A good dictionary contains many words with beginning with nephel- or nepho- which have to do with clouds. Both prefixes are Greek derivatives of the Indo-European root nebh- (``cloud''). Other offshoots lead to the Latin words nebula and nimbus and the Old Norse Niflheim.

Meteorological Terms

A number of words with the Greek root have been used in the study of terrestrial weather: These are taken from multiple sources; dates of origin are shown where available.

Interstellar Extrapolations

A few years ago, Linsky & Wood (1996 ApJ 463, 254) invented a new word, astronephography, to describe the 3-D mapping of interstellar clouds, in direct analogy to geography's mapping of the Earth. Here astroneph- translates literally as ``star-cloud'', which should be interpreted as clouds among the stars, not as clouds of stars (though, before their nature was understood, galaxies outside the Milky Way used to be called nebulae along with true interstellar clouds of gas and dust).

While the new word rolls off the tongue nicely, it doesn't mesh with the meteorological labels. Linsky & Wood's work did not involve the direct imaging which nephography implies, but rather some clever model construction based upon careful studies of stellar spectra. Agreement with the older nomenclature is hardly mandatory of course, but here's what an alternative scheme which strives to remain consistent might look like:

Of course, since nebula in modern usage refers to star-clouds rather than terrestrial clouds, the astro- prefix may be redundant in all of these. But then what fun is that?


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