At the equator, the sun is directly overhead at noon on these two equinoxes. The "nearly" equal hours of day and night is due to refraction of sunlight or a bending of the light's rays that causes the sun to appear above the horizon when the actual position of the sun is below the horizon.

On June 21, the equator has 12 hours of day and 12 hours of night. 9. On June 21, there are 24 hours of daylight in the Arctic Circle.