The passage or astronomical transit

Astronomical phenomenon, during which from the point of view of an observer of one celestial body passes in front of another celestial body, obscuring part of it.

The condition of passing of one planet by the solar disk when observing with the other is that the mutual inclination of the orbits of these planets was less than the difference of the angular size of the radius of the Sun visible from one and from another planet. For example, for the observer, this must only occur with mercury and Venus passing before the Sun. When this planet appears from Earth as a small black speck moving over the Sun.

In the General case, a transit occurs when a smaller body passes in front of the large size and the name is correct, for example, satellites (the ISS transit over the solar disk, etc.)

Translated by «Yandex.Translator»