When do transits of Venus happen?

 

Vocabulary

Orbit- The path taken by a planet around the Sun.

Transit- The movement of a planet across the face of the Sun as viewed from Earth. The dark spot of the planet is much smaller than the disk of the Sun.

Eclipse- The blockage of sunlight shining on one planet due to a second planet or moon located temporarily between them. For a solar eclipse, the moon is between Sun and Earth and its black disk matched the size of the Sun almost exactly, unlike a transit where the black disk is much smaller than the Sun.

Synodic Period- The time interval between planetary conjunctions with the Sun when the same pattern is repeated as viewed from Earth.

Conjunction- When a planet is closest to the Sun as viewed from Earth.

Conjecture- An idea which seems reasonable but has not been mathematically or scientifically proven.