The evening terminator from Messier A to Taruntius

Though not on my programme, the appearance of the topographical features in the neighbourhood of Secchi and the larger formation Taruntius on the morning of 1987 February 17 prompted me to attempt a representation which is shown opposite.

The diversity in the shape of lunar craters of medium size is sometimes quite remarkable and the formation Secchi is noticeably of irregular form, being open to the north and south with sensibly linear sections of wall on the western side. This deformation from circularity shows well under low evening light, being emphasised by the growing shadows as indicated in the drawing.

The marial ridges form an interesting subject although the advance of sunset at this stage of lighting demands rapid attention if they are to be shown correctly. It will be noted that these ridges display smooth winding configurations which are well defined and their linkage to features south of Taruntius might be worth closer study.

The outer western ramparts of Taruntius and environs were depicted during the second observing session; the low Sun brings out well the characteristics of the broad glacis which are scored with narrow valleys and enlargements or ‘pockets’.

The Mare Spumans under advancing evening light

The Mare Spumans or ‘Foaming Sea’ is a relatively little known region and one that is rarely, if ever, the subject of representation by the amateur lunarian.