Apex

A·pex

Apex

n.

pl. Apexes, Apices

  1. The tip, top, point, or angular summit of anything; as, the apex of a mountain, spire, or cone; the apex, or tip, of a leaf.
  2. The end or edge of a vein nearest the surface. (Mining) [U.S.]

Phrases & Compounds
Apex of the earth's motion
that point of the heavens toward which the earth is moving in its orbit.