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From: Kenny.OSNI@SYSTEM-M.PHOENIX.HONEYWELL@sri-unix.UUCP
Newsgroups: net.space
Subject: Language
Message-ID: <4552@sri-arpa.UUCP>
Date: Thu, 25-Aug-83 13:26:00 EDT
Article-I.D.: sri-arpa.4552
Posted: Thu Aug 25 13:26:00 1983
Date-Received: Mon, 29-Aug-83 20:37:17 EDT
Lines: 26

From:      Kevin B. Kenny    <Kenny.OSNI @ SYSTEM-M.PHOENIX.HONEYWELL>

While attempting to explain why a belt would be stable and a shell
wouldn't be (in the discussion about objects around Vega), I used the
terms "aphelion" and "perihelion" for the points in an orbit furthest
from and closest to the primary.  My friend pointed out that since
"Helios" is _the_ Sun (i.e., _our_ sun), I should have rather said
"apastron" and "periastron".  That means we have the following set of
terms:

Earth: apogee, perigee.
Moon (i.e., _our_ moon): apolune, perilune (a solecism favoured by NASA)
                 -or-    apocynthion, pericynthion (correct but obscure)
                 -or-    aposeleneion, periseleneion (hardest to spell,
                                           but the clearest in meaning).
Sun (i.e., _our_ sun, Sol/Helios): aphelion, perihelion.
Stars in general: apastron, periastron.

I have also seen "apocythereion, pericythereion" (pronounced,
incidentally, with a hard "c") applied to Venus (correct, I suppose, but
extremely obscure).

Is there a good pair of terms to use for the apsides irrespective of the
identity of the primary?

/k**2  (Kenny.OSNI%PCO-Multics@CISL-Service-Multics)