Editing Tycho (lunar crater) (section)

==Age and description==
Tycho is a relatively young crater, with an estimated age of 108&nbsp;million years ([[Annum|Ma]]), based on analysis of samples of the crater ray recovered during the {{nobr|[[Apollo 17]]}} mission.<ref name=lro/> 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.<ref>
{{cite news
 | date=September 5, 2007
 | title=Breakup event in the main asteroid belt likely caused dinosaur extinction 65 million years ago
 | publisher=[[Physorg]]
 | url=http://www.physorg.com/news108218928.html
 | access-date=2007-09-06
}}
</ref>
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.<ref>{{cite news |last=Plotner |first=Tammy |date=2015-12-24 |title=Did asteroid Baptistina kill the dinosaurs? Think other-WISE |website=[[Universe Today]] |url=https://www.universetoday.com/89050/did-asteroid-baptistina-kill-the-dinosaurs-think-other-wise/#more-89050}}</ref>

The crater is sharply defined, unlike older craters that have been degraded by subsequent impacts. The interior has a high [[albedo feature|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&nbsp;kilometers. Sections of these rays can be observed even when Tycho is illuminated only by [[planetshine|earthlight]]. Due to its prominent rays, Tycho is mapped as part of the [[Copernican period|Copernican System]].<ref>{{cite report |author1=McCauley, John F. |author2=Trask, Newell J. |year=1987 |title=The Geologic History of the Moon |editor-link=Donald Wilhelms |editor=Wilhelms, D.E. |publisher=[[United States Geological Survey]] |series=Professional Paper |volume=1348 |at=Plate&nbsp;11: Copernican system |url=https://pubs.er.usgs.gov/publication/pp1348 }}</ref>

[[Image:Tycho Crater.jpg|thumb|left|250px|The large [[ray 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 [[Terrace (geology)|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 [[Astrophotography|photograph]]s of the floor show that it is covered in a criss-crossing array of cracks and small hills. The central peaks rise {{convert|1600|m|ft|sp=us}} 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.

[[Image:Tycho Crater Panorama.jpg|thumb|Panoramic view of the lunar surface taken by {{nobr|[[Surveyor 7]],}} which landed about {{convert|29|km|mi|abbr=on}} from the rim of Tycho]]

The rim of this crater was chosen as the target of the {{nobr|[[Surveyor 7]]}} mission. The robotic spacecraft safely touched down north of the crater in January&nbsp;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 {{nobr|[[Lunar Orbiter 5]].}}

From the 1950s through the 1990s, NASA aerodynamicist Dean Chapman and others advanced the lunar origin theory of [[tektite]]s. 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 [[Antonius Maria Schyrleus de Rheita|A.M.S. de&nbsp;Rheita]] depicted the bright ray system.