Tycho is a prominent crater on the side of the Moon that permanently faces the Earth.
Tycho is believed to have formed about 100 million years ago, when an asteroid or comet slammed into the Moon. Material from the impact fell back to the surface as bright rays of ejecta. The rays are visible from Earth with the naked eye, although the crater itself is too small to be seen.
Early lunar maps identified Tycho as a region of interest for exploration. A probe from Earth, Surveyor 7, landed just north of Tycho crater in 1968. A follow-up manned Apollo landing was proposed in 1969, but later canceled on the grounds that the lunar surface was too rugged in that area.