Here's why:

* Earth's Tilt: The Earth is tilted on its axis at approximately 23.5 degrees. This tilt is the reason we have seasons.

* Orbit: The Earth orbits the sun in an elliptical path. This means that sometimes we are closer to the sun than other times.

Because of these factors, the Earth only directly faces the sun at the equator during the equinoxes (around March 20th and September 22nd). At other times of the year, the sun's rays hit the Earth at an angle, depending on the time of year and your location on the planet.