It's daytime on Earth when a specific location on Earth is facing the sun.

Here's why:

* Earth's Rotation: The Earth rotates on its axis, completing a full rotation approximately every 24 hours.

* Facing the Sun: As the Earth spins, different parts of the planet face the sun, resulting in daytime.

* Day and Night: When a location on Earth faces the sun, it experiences daytime. When that location is facing away from the sun, it experiences nighttime.

Therefore, it's not the entire Earth that faces the sun at the same time, but rather specific locations.