Transit of Venus, 8th June 2004. The sun is being projected onto a sheet of paper for safe viewing. Venus is the small black dot seen in the lower portion of the Sun. A transit occurs when Venus passes in front of the Sun as seen from Earth. This was the first transit since 1882. Venus is an Earth-sized planet that orbits in between Earth and the Sun. It does not appear to cross the Sun's disc during every orbit as the orbital paths of the Earth and Venus are not in exactly the same plane. Venus transits occur in pairs separated by eight years, with alternating intervals of 121.5 and 104.5 years in between pairs.