There is a misunderstanding in the question. There are no planets that are both a "morning star" and an "evening star". The terms "morning star" and "evening star" refer to the same celestial object: Venus.

Here's why:

* Venus is the brightest planet in our solar system, and its visibility depends on its position relative to the Sun and Earth.

* When Venus is located between the Earth and the Sun (in its "inferior conjunction"), it's not visible.

* As Venus moves away from the Sun, it appears in the western sky after sunset, earning the name "evening star".

* As Venus continues its orbit, it appears in the eastern sky before sunrise, becoming the "morning star".

So, Venus is the only planet that can be both a "morning star" and an "evening star" at different times in its orbit.