The axis of Earth's rotation tilted all year perpendicular to the plane of the Earth's orbit around the sun. The angle is 23. 5°. Because of this angle on December 22 the northern hemisphere has its winter solstice and the southern hemisphere has its summer solstice, and the latitude 23. 5°S is the farthest point south at which directs sunlight hits. On June 22 the northern hemisphere has its summer solstice and the southern hemisphere has its winter solstice, and the latitude 23. 5°N is the farthest point north that hit be direct sunlight hits. An animation illustrates this. ,