February 27, 2018

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A Wondrous Image

Originally published September 26, 2008 LPOD-2005-04-03.jpeg
image by Gerardo Sbarufatti
This is a repeat of a classic LPOD from April 3, 2005

Like a comet, the Oppel Ridge widens and becomes less conspicuous where it streaks away from a small nameless crater along the northern shore of Mare Crisium. Oppel is part of the circular mare ridge system that defines a 375 km wide inner ring of the Crisium basin, but its character seems different than the other ridges. In this marvelous low sun view it appears superimposed upon the topography. Its edges are partially marked by ridges and the center part is like a raised welt – its elevation is emphasized by its brightness as the surrounding maria darkens as the terminator is approached. The low sun also brings out a feature I’ve never noticed before – a slot-like depression north of the Oppel Ridge. The best Lunar Orbiter 4 view shows this only as a low area bounded by two ridges, but it is obviously an undiscovered graben. Where the graben reaches the basin shore, Crisium’s normal blocky mountains (massifs) appear rounded and dome-like, and both of these rounded hills has a summit pit. I don’t think these hills are volcanoes (although they do look something like the Gruithuisen volcanic domes), but they are surprising. Wow! Every great image like this teaches me more about the Moon! I want to learn more so I encourage everyone to take more low sun images of insufficiently explored regions like this!

Chuck Wood

Technical Details
March 13, 2005. Celestron 8 + 2X Barlow + Phillips Vesta Pro + 4,400 mm red filter. DivX AVI 200 sec @ 10fps, 1800 frames. This image was taken with a garden variety 8" telescope!

Related Links
Rükl plate 26

Yesterday's LPOD: The Moon On Earth

Tomorrow's LPOD: Peak


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