The ecliptic is the path followed yearly by the sun against the background of relatively fixed stars, as seen by an observer on Earth. The ecliptic forms the center of the zodiacal band.
The two points in space where the plane of the Earth's rotation crosses the ecliptic are known as the Vernal and Autumnal equinoxes. In Western or Tropical Astrology, the first point of Aries, the beginning of the zodiac, is always at the Vernal Equinox. In Eastern or Sidereal Astrology, Aries begins at a point defined relative to the position of some relatively fixed star.