An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

The direction in the sky (in → Columba) away from which the Sun seems to be moving (at a speed of 19.4 km/s) relative to general field stars in the Galaxy.

Antapex from L. ant-, → anti- "against, opposite," + L. → apex "summit, peak, tip."

Pâdcakâd from pâd-, → anti- + cakâd "summit of a mountain; top, crown of the head, top of the forehead," from Mid.Pers. cakât "summit," → apex.

1) General: The highest point or level.
2) Mathematics: The highest point of a geometric figure or solid relative to some line or plane.
3) Astro.: Solar apex. The point on the celestial sphere toward which the Sun and the solar system are moving relative to the stars in our vicinity.

L. apex "summit, peak, tip," probably related to apere "to fasten, fix," hence "the tip of anything".

Cakâd "summit of a mountain; top, crown of the head, top of the forehead," from Mid.Pers. cakât "summit," cf. Skt. kakud-, kakuda- "peak, summit," L. cacumen "top, point," cumulus "heap."

The apparent direction (in the constellation → Columbia) away from which the Sun is moving in its orbit around the center of the Galaxy. → solar apex.

→ solar; → antapex.

The point on the celestial sphere toward which the Sun is apparently moving relative to the → local standard of rest. Its position, in the constellation → Hercules, is approximately R.A. 18h, Dec. +30°, close to the star → Vega. The velocity of this motion is estimated to be about 19.4 km/sec (about 4. AU/year). As a result of this motion, stars seem to be converging toward a point in the opposite direction, the → solar antapex.

→ solar; → apex.