Copernicus 9.7°N, 20.1°W

Copernicus is perhaps the most impressive example of a young, large complex crater, and which was formed about 800 million years ago. It lies between the southern side of Mare Imbrium and the northern portion of Mare Insularum, which has no distinct boundaries and merges into Oceanus Procellarum and Mare Nubium.

Copernicus has a diameter of 93 km and distinctly terraced inner crater walls, which tower 3.7 km above the crater's floor. A group of central mountains reaches up to heights of 1.2 km above the floor. The height of the outer ramparts amounts to only about 900 m. The southern portion of the crater's floor is saturated with a vast number of small hills, but the northern portion, by contrast, seems extremely smooth, level and structureless. It has probably been flooded by lava. The ratio of its depth to diameter of 1:25 (known as Schröter's Rule) corresponds more closely to that of a flat plate, rather than to the section of a bowl or funnel. When the Moon's age is about 9 to 10 days, a small lunar dome becomes visible about 90 km west of Copernicus. A large number of smaller secondary craters, crater pits and depressions lie in the terrain to the northeast of Copernicus. They were created by secondary impacts. A bright, extensive and very complex ray system becomes visible around the crater under high solar illumination.