When We See Venus


As you learned earlier, Venus and Mercury- the two planets that lie between the Earth and Sun, are visible in the morning and evening. When they can be seen depends on the position of the planets relative to Earth and the Sun!

The following diagrams help to explain why we see Venus when we do. Refer to the "Help Box" to understand the parts of the diagrams.


Dotted lines in diagrams represent lines of sight from Earth to Venus in the morning and evening.


Diagram 1

Diagram 1: When Venus is directly between the Earth and Sun, we see it in the morning and evening sky. This is because in the early morning or evening, we can see a partial reflection of the Sun's light off of Venus' surface.


Diagram 2

Diagram 2: When Venus is on either side of the Sun, and not between the Sun and Earth, it is visible only one time per day. In the case above, Venus is visible during the evening and you can't see Venus in the morning because the curvature of the Earth forbids it.


Diagram 3

Diagram3: In the above diagram, Venus is only visible in the morning sky. Again, the curvature and rotation of the Earth prevents it from being seen in the evening.


There are also times where Venus is not visible at all. Can you think of a place in Venus' orbit where we could not see it?

We would not be able to see Venus if it lies on the opposite side of the Sun than Earth. The Sun's brightness would prevent it from being seen at all times!

When the Sun comes between Earth and Venus, there is no path of sight, morning or evening, where we can find Venus.


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