Animation comparing Venus and Earth. The positions of Earth and Venus are shown, before they are shown to scale with the Sun. Venus is the second planet from the Sun, Earth is the third. Venus has a diameter 650 kilometres less than that of Earth磗. Their distances from the Sun are then shown, before Venus is shown transiting the Sun. A transit occurs when Venus passes in front of the Sun as seen from Earth. Transits by Venus across the Sun are rare, occurring in 8_year pairs separated by more than 100 years. Transits in the modern era occurred in 1874 and 1882, and 2004 and 2012. The next pair of transits will occur in 2117 and 2125.