Römer (crater)

Römer is a lunar impact crater located in the northeastern part of the Moon, near the eastern limb. It lies to the southwest of the larger crater Alexander, and northeast of the slightly smaller crater Picard.

The crater is named after the Danish astronomer Ole (or Olaus) Christensen Römer, who made the first quantitative measurements of the speed of light in 1676.

Römer is a relatively well-defined crater with a sharp rim, a slightly terraced inner wall, and a somewhat irregular floor. The rim is roughly circular, though it exhibits some minor irregularities and outward bulges, particularly along its eastern side. Small impact craters lie along the rim edge, mainly in the south. The crater floor is marked by several small impacts and a low central peak.

The area surrounding Römer is relatively smooth, typical of lunar maria. The crater's location near the limb makes it subject to foreshortening when viewed from Earth.