Copernicus

Copernicus is the type crater of the Copernican period, the youngest division of the lunar timescale. The boundary is drawn where rays are still bright, so the definition rests on a property that fades: ejecta darkens as micrometeorites and the solar wind mature it, and a crater leaves the Copernican by becoming dull rather than by any event. Copernicus itself is about 800 million years old.

The 96 km bowl reaches 3.8 km below the rim, with terraces cut by slumping of the wall and a floor covered in solidified impact melt. Its central peaks are olivine-rich, material lifted from below the mare basalt, which is why the peak spectrum does not match the surrounding plain.