* Earth is a sphere: Our planet is a round ball. This means that only half of the Earth is facing the sun at any given moment. The other half is facing away from the sun, experiencing night.
* Rotation: Earth constantly spins on its axis, taking roughly 24 hours to complete one full rotation. This spinning movement is what causes day and night. As Earth turns, different parts of the planet are exposed to the sun's light.
Think of it like this: imagine a giant flashlight shining on a ball. Only the half of the ball facing the flashlight is illuminated, while the other half is in darkness.
That's why people in different parts of the world have different times of day, even though it's the same moment for the entire planet.
