aphelion n.

before vowels ap-, word-forming element meaning "of, from, away from; separate, apart from, free from," from Greek apo "from, away from; after; in descent from," in compounds, "asunder, off; finishing, completing; back again," of time, "after," of origin, "sprung from, descended from; because of," from PIE root *apo- "off, away" (source also of Sanskrit apa "away from," Avestan apa "away from," Latin ab "away from, from," Gothic af, Old English of "away from," Modern English of, off).

*sāwel-, Proto-Indo-European root meaning "the sun." According to Watkins, the *-el- in it originally was a suffix, and there was an alternative form *s(u)wen-, with suffix *-en-, hence the two forms represented by Latin sol, English sun.

It forms all or part of: anthelion; aphelion; girasole; heliacal; helio-; heliotrope; helium; insolate; insolation; parasol; parhelion; perihelion; Sol; solar; solarium; solstice; south; southern; sun; Sunday.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit suryah, Avestan hvar "sun, light, heavens;" Greek hēlios; Latin sol "the sun, sunlight;" Lithuanian saulė, Old Church Slavonic slunice; Gothic sauil, Old English sol "sun;" Old English swegl "sky, heavens, the sun;" Welsh haul, Old Cornish heuul, Breton heol "sun;" Old Irish suil "eye;" Avestan xueng "sun;" Old Irish fur-sunnud "lighting up;" Old English sunne German Sonne, Gothic sunno "the sun."

"point at which the moon is farthest from the earth," 1590s, from French apogée or directly from Latin apogaeum, from Greek apogaion (diastema) "(distance) away from the earth," from apogaion, neuter adjective, "from land," here in a specialized sense "away from the earth," from apo "off, away" (see apo-) + gaia/ge "earth" (see Gaia).

The figurative sense of "climax, culmination" is from 1640s. A term from Ptolemaic astronomy, which regarded the earth as the center of the universe and applied the word to the sun and planets; for these bodies it was displaced in the Copernican system by aphelion. Adjective forms are apogeal, apogean, apogeic.