Here's why:
* Venus is not a light source: It reflects sunlight.
* Venus orbits closer to the Sun than Earth: This means it's always relatively close to the Sun in the sky.
* Venus's position relative to the Sun changes over time: Sometimes it's visible in the evening sky after sunset, and sometimes in the morning sky before sunrise.
So, while you might technically see Venus in the night sky during these periods of visibility, it's actually more accurate to call it evening or morning twilight.