ABSTRACT
Copernicus (Fig. 26.1) is another striking ray-crater, nearly as big as Tycho. Although the rays of Copernicus are not as long as those of Tycho, their visibility is enhanced by their trespassing across the dark floors of Mare Imbrium, Sinus Aestuum and the northern parts of Oceanus Procellarum where they join the rays of Aristarchus and Kepler (31 km in diameter). The ray-elements (Fig. 26.3) of Copernicus trace back to its annular floor, which surrounds the central mountains (Fig. 33.1). Several lava flows may again be recognised, some having run inwards down the north wall terraces. Again, there are lava lakes in and around the walls of Copernicus. The lavas would rise under the hydrostatic pressure caused by the burden of the ringwalls.
