This animation represents the movement of Earth (outside, blue) and Venus (inside, orange) around the Sun, from January 1, 2000 to December 31, 2029. One white line is drawn from one planet’s position to the other’s every five days. The circles represent the orbit of each planet if they were perfectly circular—the difference is noticeable for Earth’s orbit, but not so much for Venus’s.

A five-lobed pattern appears rapidly; however, we let the animation run for longer to illustrate that it’s not perfect and slowly “turns” with respect to the Sun.

The plane of Venus’s is not the same as the plane of Earth’s orbit (the ecliptic), so we don’t see Venus pass in front of the Sun each time the planet is between our star and us. As a matter of fact, such a transit is a very rare phenomenon: The last two occurrences were 2004 and 2012, and the next ones will be 2117 and 2125.