It is useful to plot the path of Venus taking the earth as fixed. To do this, first draw two arrows, the first from Earth to the sun, the second from the sun to Venus:



Venus moves on a little circle the center of which moves on a big circle around the earth.

The result.

Here we see a small circle of radius 0.723 AU that revolves about the earth (at the center). The center of the small circle moves along a big circle of radius 1.00 AU once each year. Venus, represented as a red dot, revolves about the center of the small circle once every 0.615 years. After the point of closest approach, I have changed the red dot to a blue dot for clarity.

Connecting the dots gives the path of Venus relative to the earth.

Here is the path of Venus relative to the earth over 8 Earth years (which is 13 Venus years).

Here is what we get if we plot the position of Venus on the celestial sphere on successive days.

Prediction for what we see.

For a while we see Venus in the evening sky. Then it appears in the morning sky. Here is a picture of what we would see on successive nights one hour after sunset.


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Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA soper@bovine.uoregon.edu