aphelion Astr.
(əˈfiːlɪən)
Pl. aphelia.
[Græcized form of mod.L. aphēlium, f. Gr. ἀϕ' = ἀπό off, from + ἥλιος sun; formed, by Kepler, after the apogæum, ἀπόγαιον, of the Ptolemaic astronomy (see Prodr. dissert. cosmographicarum, 1596, and Epitome astronom. Copernic. 1618). Aphelium was also the earlier form in Eng.; cf. parhelion, Gr. παρήλιον. Fr. has aphélie, like apogée.]
1. That point of a planet's or comet's orbit at which it is farthest from the sun.
| 1656 tr. Hobbes's Elem. Philos. (1839) 443 The apogæum of the sun or the aphelium of the earth ought to be about the 28th degree of Cancer. 1676 Halley in Rigaud Corr. Sci. Men I. 237 The Aphelion, Eccentricities, and Proportions of the Orbs of the Primary Planets. 1794 Sullivan View Nat. II. 410 Of these distances, the least of all is called the perihelium, and the greatest the aphelium. 1837 Whewell Hist. Induct. Sc. (1857) II. 131 The aphelia of Mercury, Venus, the Earth, and Mars, slightly progress. 1880 Wallace Isl. Life viii. 132 The effect is intensified by winter being there in aphelion. |
2. fig.
| 1845 H. Rogers Ess. I. iii. 137 The dark aphelion of the eccentric orbit in which the church of Christ had wandered. 1858 Gen. P. Thompson Audi Alt. II. lxxvi. 29 France, which is just now in what astronomers call the aphelion or furthest point of political cold. |