The equator of the earth, when extended into space is called the celestial equator. The yearly migration of the sun around the ecliptic causes the daily path of the sun to vary. When the sun is at its northernmost position with respect to the equator, the sun rises in the northeast, travels nearly overhead and sets in the northwest. Days are long and nights short. When the sun is at its southernmost position with respect to the equator, it rises in the southeast, passes low in the south at noon and sets in the southwest.
Days are short and nights are long.
Twice a year, the sun appears exactly on the equator. On or about March 21, the sun appears to cross the equator from south to north. On or about September 23, the sun appears to cross the equator from north to south. When it appears on the equator, the sun rises exactly in the east and sets exactly in the west. It is above the horizon for twelve hours each day and below the horizon for twelve hours.