Here's why:

* Morning and evening stars are Venus: The terms "morning star" and "evening star" refer to the planet Venus, which appears bright in the sky before sunrise (morning star) or after sunset (evening star).

* Jupiter is a different planet: Jupiter is a much larger planet than Venus, and while it can be very bright, it doesn't have the same close relationship with the sun that makes Venus appear as the morning and evening star.

While Jupiter can appear bright and be visible in the sky at various times, it's not considered the morning or evening star.