Tycho is a relatively young crater, with an estimated age of 108 million years (
Ma), based on analysis by NASA's Lunar Reconnaissance Orbiter spacecraft. This age initially suggested that the impactor may have been a member of the
Baptistina family of asteroids, but as the composition of the impactor is unknown this remained conjecture. However, this possibility was ruled out by the
Wide-field Infrared Survey Explorer in 2011, as it was discovered that the Baptistina family was produced much later than expected, having formed approximately 80 million years ago. The crater is sharply defined, unlike older craters that have been degraded by subsequent impacts. The interior has a high
albedo that is prominent when the Sun is overhead, and the crater is surrounded by a distinctive
ray system forming long spokes that reach as long as 1,500 kilometers. In absolute mileage terms, Tycho's ejecta field is approximately the same size as the K-Pg impactor ejecta field, and in proportional terms, the only terrestrial feature of comparable size is the Pacific Ocean. Sections of these rays can be observed even when Tycho is illuminated only by
earthlight. Due to its prominent rays, Tycho is mapped as part of the
Copernican System. centered on Tycho The ramparts beyond the rim have a lower albedo than the interior for a distance of over a hundred kilometers, and are free of the ray markings that lie beyond. This darker rim may have been formed from minerals excavated during the impact. Its inner wall is slumped and
terraced, sloping down to a rough but nearly flat floor exhibiting small, knobby domes. The floor displays signs of past volcanism, most likely from rock melt caused by the impact. Detailed
photographs of the floor show that it is covered in a criss-crossing array of cracks and small hills. The central peaks rise above the floor, and a lesser peak stands just to the northeast of the primary
massif. Infrared observations of the lunar surface during an eclipse have demonstrated that Tycho cools at a slower rate than other parts of the surface, making the crater a "hot spot". This effect is caused by the difference in materials that cover the crater. The rim of this crater was chosen as the target of the mission. The robotic spacecraft safely touched down north of the crater in January 1968. The craft performed chemical measurements of the surface, finding a composition different from the maria. From this, one of the main components of the highlands was theorized to be
anorthosite, an
aluminium-rich mineral. The crater was also imaged in great detail by From the 1950s through the 1990s, NASA aerodynamicist Dean Chapman and others advanced the lunar origin theory of
tektites. Chapman used complex orbital computer models and extensive wind tunnel tests to support the theory that the so-called Australasian tektites originated from the Rosse ejecta ray of Tycho. Until the Rosse ray is sampled, a lunar origin for these tektites cannot be ruled out, though tektites are now generally considered to have been produced by terrestrial impact events. This crater was drawn on lunar maps as early as 1645, when
A.M.S. de Rheita depicted the bright ray system. == Names ==