Sun directly overhead on equator at two times of year, the March and September equinoxes . Noon sun is highest in our sky on this date. C. Daylight periods 1. At any given time, half the earth is illuminated by the sun and half the earth is in darkness. Every point on the earth's surface experiences 12 hr. of daylight and 12 hr. of darkness.
Circle of illumination passes directly over poles.
Daylight period gets progressively longer northward, moving from Antarctic to Arctic Circle. Arctic Circle northward experiences 24 hr darkness, Antarctic Circle southward 24 hr daylight. Daylight gets progressively shorter northward. Daylight period generalizations Annual variation in daylight period becomes increasingly variable moving from equator to poles. Sun rises and sets each day, never directly overhead.