Earth rotates on its axis once every 24 hours, receives light when facing the sun (day), circle of illumination, night is shadow side

Rotation axis of the Earth is tilted 231/2 ° away from perpendicular to plane of ecliptic; The north pole always points to the North Star (Polaris); one pole is facing toward the sun while the other pole is tilted away from the sun; the N pole faces the sun when the sun is between the Earth and the North Star, but faces away from the sun when the Earth is between the sun and the North Star.

tilt of rotation axis and circle of illumination; long in summer, short in winter (solstice); 12 hours in spring and autumn (equinox); noon sun angle