bill@utastro.UUCP (10/04/83)
Mark Brader (dciem!ntt) asked me to post the following, with additions, in response to his letter to me asking whether the IAU has an official position with regard to names for the Sun, Moon, etc., and about capitalization of these names. I have checked my understanding with Dr. J. D. Mulholland, who is most knowledgeable about these things, and this is how it shapes up: The IAU has never taken a stand on the names of the Sun, Moon, Earth or Galaxy since these names (with the exception of the latter) were in common use for centuries and are simply part of the language. As to capitalization, the common practice until about 1940 was to capitalize, at which point the grammarians took over the editorial offices of the various journals, and "sun", "moon" and "earth" were no longer capitalized. Mulholland himself feels (and I agree with him) that this is a foolish exercise in pedantry, and he fought a battle with the editor of the Astronomical Journal which resulted in its adopting a neutral policy with regard to capitalization, i.e., whatever the author wants is what he gets. As to the definite article, it is invariably used. The word "Galaxy" is invariably capitalized to distinguish it from other galaxies, and again it takes the definite article. In addition, one often sees "The Milky Way" - again, this is an ancient name. To summarize: You can capitalize or not as you see fit; some editors may care, but the IAU doesn't; use the definite article; always capitalize Galaxy or Milky Way when referring to our stellar system. Mark also asked me to comment further on peri- and apo- words, and I am happy to do so. First, "pericenter" and "apocenter" can *always* be used, regardless of the primary. Except for these words, a particular primary is always meant. Thus I have heard or seen in print the following (some, such as peribarythron and peribothron are strictly "unofficial"): Term Primary pericenter, apocenter Any primary perilune, apolune, Moon (Lat. "luna" - Moon) pericynthion, apocynthion Moon (Lat. "Cynthia" - Moon) pericytherion, apocytherion Venus (Grk. "Cytheria" - Venus) perijove, apojove Jupiter (Lat. "Jove" - Jupiter) perisaturnium, aposaturnium Saturn perihelion, aphelion Sun (Grk. "Helios" - Sun) perigee, apogee Earth (Grk. "Geos" - Sun) periastron, apastron any star (Grk. "Astron" - star) perigalacticon, apogalacticon the Galaxy peribarythron, apobarythron, a black hole (Grk. "bary" - heavy) peribothron, apobothron a black hole (Grk. "bothros" - a bottomless pit) In general, Greek roots are preferable to Latin since peri- and apo- are Greek affixes. I like "peribothron" much better than "peribarythron" - there is a bottomless pit with this name in mythology. It is also common to talk about the "perigee of the Sun in its orbit around the Earth", since for certain purposes in celestial mechanics this is a useful concept, even if it contradicts the Newtonian picture. Bill Jefferys 8-% Astronomy Dept, University of Texas, Austin TX 78712 (Snail) ihnp4!kpno!utastro!bill (uucp) utastro!bill@utexas-11 (ARPA)