Here's why:

* Earth's Tilt: The Earth is tilted on its axis. This tilt causes the sun's apparent position in the sky to change throughout the year.

* Equator's Position: The equator is the imaginary line that circles the Earth at 0 degrees latitude. It's the only place where the sun rises directly east and sets directly west on the equinoxes (March 20th and September 22nd).

Important Note: While the sun will rise directly east on the equator during the equinoxes, it will rise slightly north of east in the Northern Hemisphere and slightly south of east in the Southern Hemisphere at other times of the year.