Hills in the middle
Impact craters are by far the most abundant landforms on the Moon. Thousands of them having diameters larger than about 5 kilometres are visible through almost any backyard telescope. All can be classified into three fundamental types by inspecting their interior zones — the walls, floors and central peak elevations.
Most lunar craters are bowl-shaped simple craters with diameters up to about 15 km. They have featureless walls, rounded or flat floors, and no central hills. Piazzi Smyth, for example, is a 13-km simple crater in southern Mare Imbrium.
are larger than simple craters, and you need to observe their interiors closely
