The Transit of the Venus over the disk of the Sun is something like the eclipse of the Sun. The heavenly body covering the Sun isn’t Moon but planet Venus. Actually the distance of the Venus from the Earth is reason why this phenomenon is far less visible than the eclipse of the Sun. In practise it means that black circle thirty-times smaller than the disk of the Sun passes over.

The Transit of the Venus over the disk of the Sun is uncommon. The pairs of transits distant 8 years apart return in turns 121, 5 and 113, 5 years. Next of the topical transits will come in 2012 and if we know the last transit of Venus was seen in 1882, we can count the future date easily, it will be in 2117.

For being that natural phenomenon the several conditions must be accomplished. The first one is that the Sun, the Venus as well as the Earth have to find in the one line. Because the orbit of Venus is against the orbit of the Earth reclined to 3, 4 degrees, the Venus must be near one of its two centres of the orbit. Only combinations of these two conditions guarantee the illusive projection of the Venus on the disk of the Sun.