Here's why:
* Rotation: All planets in our solar system rotate on their axis. This rotation creates the cycle of day and night.
* Sunlight: Planets are illuminated by the sun. While some planets have very long days and nights, they still experience periods of light and darkness.
However, there are a few things that might make you think a planet has no day or night:
* A planet tidally locked to its star: This means one side of the planet always faces the star, resulting in a perpetual day on that side and a perpetual night on the other. Mercury is a good example of a planet that is partially tidally locked.
* A planet with an extremely slow rotation: If a planet rotates very slowly, its days and nights could be incredibly long, perhaps even lasting years.
Let me know if you have any other space-related questions!
