Gauss. The walled-plain at sunset

A magnificent walled-plain, fully 110 miles in diameter at mean position 36° N 79° E which would be a most imposing object if more centrally placed. Even so, foreshortening is not so acute that interior details are difficult to make out and, when conditions are really favourable, as in the present observation, then there is much to record under good seeing with even quite moderate aperture.

Due to its size, the comparatively smooth floor shows well the curvature of the lunar globe, and, under oblique evening illumination, there is a need for haste when recording details, as noticeable changes take place in as little as 15 minutes on the rapidly darkening floor.

The main topographical features of the interior should be self-explanatory from the accompanying drawing but there was a multitude of much finer details which, although glimpsed in the better moments, could not be depicted with any certainty and which it was preferable to omit rather than indicate in a dubious representation.

The interior is commended to the interested reader who has the necessary equipment.

Mare Humboldtianum and Belkovitch

The Mare was called appropriately Humboldtianum after the explorer Alexander von Humboldt whose discoveries linked the Earth's eastern and western hemispheres. This ‘sea’ links the near and averted sides of the Moon.