Vol 50, No 5, May 2013 - BAA Lunar Section

From the DirectorThe April issue of the LSC contained much material of interest to those fascinated by lunar topographic oddities.In particular I was struck by Damian Peach’s fine image of the Hevelius region, taken on 2012 December 26, andby the selection of material submitted by Richard Baum relating to the feature known informally as ‘Larrieu’sDam’. Nigel Longshaw has written about the latter in a fine paper in the BAA Journal (Vol. 118, No. 2, 2008 April),and Damian’s image includes a feature that has also caught Nigel’s attention in the past – the so-called ‘MiyamoriValley’ (see the BAA Journal, Vol. 118, No. 6, 2008 December). Both ‘Larrieu’s Dam’ and the ‘Miyamori Valley’are minor features, it must be admitted, but they have intrigued observers and challenged ready interpretation in thepast. It seemed reasonable to me to check whether the new tools available to us via the LROC Quickmap (inparticular the possibility of plotting elevation profiles) could offer new insights.Is there a ‘Miyamori Valley’?Nigel’s paper traced the observationalhistory of this linear feature runningwest from Lohrmann towardsRiccioli (Fig. 1, a crop from Damian’simage). At the telescope and underearly morning illumination it looksfor all the world like a lesser versionof the Alpine Valley, but it is almostundetectable as such on imagery fromspacecraft (Fig. 2). Nigel concludedthat it was not a valley at all, butsimply an illusion created from thechance alignment of surface features,in particular a cliff-like ridge markingthe southern edge of the ‘valley’. Heis probably right, but the LROCelevation plots suggest that the featureis valley-like along at least part of itslength. A plot taken from north tosouth at a point immediately to the2The ‘Miyamori Valley’, imaged on 2012 December 26 at 19:15 UT byDamian Peach (Fig. 1, above), and (Fig. 2, below) imaged by LunarOrbiter IV in 1967 (detail from image IV-169-H1).BAA Lunar Section Circular Vol. 50 No. 5 May 2013