An astronomical transit is the passage of a celestial body or satellite across the face of a relatively larger body. Transits are not the same thing as the familiar solar or lunar eclipse. In an eclipse, a large celestial body hides a major part of a smaller body. In an astronomical transit, a small body crosses in front of a larger one. An astronomical transit can involve two planets, but this has not been observed on Earth since 1818. When will the next planetary transit be visible from Earth? Discuss