Here's why:

* Sunlight overwhelms starlight: The sun is incredibly bright, and its light dominates the sky during the day. The faint light from stars is simply not strong enough to be seen against the sun's glare.

* Constellations are based on star patterns: Constellations are recognizable patterns of stars that are visible at night. During the day, the sun's light hides these stars from view, making it impossible to see the constellations.

However, you can sometimes see certain planets during the day if they are in the right position and the sky conditions are favorable.