aphelion (n.)

"point farthest from the sun" (of a celestial body's orbit), 1670s, a Grecianized form of Modern Latin aphelium (itself attested in English from 1650s), coined by Johannes Kepler based on Greek apo heliou "away from the sun," from assimilated form of apo "away from" (see apo-) + heliou, genitive of helios "sun" (from PIE root *sawel- "the sun"). Formed on the model of Ptolemaic apogaeum (see apogee) to reflect the new heliocentric model of the universe.

Share