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Ecliptic

The annual path of the sun through the stars. The twelve zodiac constellations are located along the ecliptic. The sun moves along this path at one degree per day relative to the stars (from 360° divided by 365 days). The First Point of Aries is astronomically defined as the intersection of the ecliptic and the celestial equator (the line across the sky that separates northern stars from southern stars). The term ecliptic is not directly used in the practice of navigation. The zodiac constellation observed on the horizon just before the rising sun and just following the setting sun tells the position of the sun along the ecliptic, and has served for thousands of years as a stellar calendar. Because the orbits of the moon and planets lie in the same plane with the earth's orbit, these bodies are also always seen along the ecliptic. Whenever the moon and planets can be seen together, they will form a line (giant arc) across the sky. At twilight, this line also includes the point on the horizon that the sun crosses. See Aries.


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