November 28, 2014

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A Final Bow

image by Damian Peach, Selsey, UK

2500 years ago the Greek philosopher Plato famously wrote about prisoners in a cave mistaking shadows for reality. We have a similar problem in looking at shadows cast when the Sun is low in the lunar sky. In Damian's superb image the sunset shadows cast by Plato's west wall can fool us into thinking that the wall's variations in elevation must be immense. Nasmyth and Carpenter made this mistake and concluded that lunar mountains were steep spires. Now we have learned to disbelieve our eyes, or at least to filter our raw perception through experience that says that grazing illumination falsely exaggerates height variations, deliciously so. Over the last decade we have gone from being fixated on how many craters pepper Plato's floor, to examining geological phenomena that previously went unnoticed. We've moved on from the shadows to reality. In previous LPODs we noticed the lighter hued layer around the top of Plato's rim, the surprising depth of the crater Bliss/Plato A, the wide rille that cuts through Plato's ejecta just this side of Mare Frigoris, and the delicate rille that starts near Plato's west side, cuts down to the mare and snakes across it towards the Teneriffe Mountains. With this low Sun image we can add another unnoticed anomaly - the massive round mountain to the northeast of Plato. This feature rises a kilometer above its surroundings and has a curved summit, suggesting that it could be the remnant of an earlier crater, although it might just as well be another huge block thrown out by the formation of the Imbrium Basin. Every image brings new surprises.

Chuck Wood

Technical Details
April 22, 2014. Celestron C14 Schimdt Cassegrain

Related Links
21st Century Atlas chart 19.
More of Damian's lunar images from 2014.
Damian's virtual presences: web, and Facebook

Yesterday's LPOD: Knocking the Moon Over

Tomorrow's LPOD: Penultimate LPOD


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