Tycho is one of the most recognizable features on the Moon’s near side, easily visible through small telescopes. This massive impact structure is distinguished by an extensive system of bright, radial rays that streak across the lunar surface for thousands of kilometers. Located in the Southern Highlands, the crater offers a look at the mechanics of a complex, large-scale impact. The features found within its walls, from the central structure to the floor material, provide scientists with an invaluable window into the Moon’s crustal composition and history.
The Crater’s Defining Characteristics
The Tycho crater is situated in the Moon’s southern uplands, at approximately 43 degrees south latitude. This impact feature measures about 85 kilometers (53 miles) in diameter and drops to a depth of around 4 kilometers (2.5 miles). Its scale places it among the Moon’s significant complex impact structures.
Its most notable characteristic is its relative youth, estimated at about 108 million years. This age is quite young compared to the billions-of-years-old lunar surface. Because it has not been subjected to prolonged degradation, Tycho’s rim remains sharp, and its internal features are well-preserved. The bright, highly visible ray system that originates from the crater is a direct result of this youth, as the ejected material has not yet been darkened by space weathering.
The Prominent Central Uplift
The most significant landform inside the Tycho crater is the central uplift, a massive mountainous complex near the center of the crater floor. This peak is a complex mound, formed not by volcanic activity but by the powerful rebound of the lunar crust immediately following the impact. The immense energy of the impact compresses the rock, and as the transient cavity collapses, the rock layers spring back upward, forming the central structure.
The central peak rises significantly above the crater floor, with elevations ranging from approximately 1.5 to 2.5 kilometers. The peak is often brighter than the surrounding floor, and its composition differs from material closer to the rim. Analysis suggests it consists of rock excavated from deep beneath the surface, far greater than the original crater depth. Scientists study these exposed rock layers because the crustal rebound acts as a natural drill core, bringing up ancient, deep-seated lunar material for observation.
Geological Materials and Floor Features
Beyond the central uplift, the crater bowl provides a textbook example of a fresh, complex impact site, featuring distinct geological materials and structures. The inner walls are characterized by terraced walls, which are step-like structures formed as unstable, fractured rock slumped inward shortly after the impact. This slumping process widened the crater and created the steep, irregular slopes descending to the floor.
The floor is covered in a coherent sheet of impact melt, a material created when lunar rock was superheated into a liquid state by the impact’s energy. This molten rock flowed and pooled across the deepest parts of the crater, cooling into a hummocky, fractured surface. Melt pools and flows are also visible draped along the terraced inner walls. The remaining floor material consists largely of breccia, a mix of rock fragments cemented together by the impact pressure. Because these features have not been covered by later impacts or regolith formation, Tycho stands out sharply compared to older, subdued craters.