Four Little Words

Lots of confusion about these hard-to-remember words.
  • Aphelion: Furthest from the Sun
    From the Greek, aphelios:
    ap = away, plus helios = the sun.
  • Apogee: Furthest from the Earth
    From the Greek, apogaios:
    ap = away, plus gaia = the earth.
  • Perihelion: Closest to the Sun
    From the Greek, perihelios:
    peri = near, plus helios = the sun.
  • Perigee: Closest to the Earth
    From the Greek, perigaios:
    peri = near, plus gaia = the earth.
    • We will be using aphelion and perihelion exclusively in this website. To remember which is which: just remember APEX.

    And by the way, apsides refers to all four points, that is, the ends of the major axis, while quadrant points refers to the ends of the minor axis.

    Rev'd 09 jan 2002 by ralph abraham