January 17, 2013

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Looking Backward

image from LRO QuickMap

There must be clouds everywhere because very few lunar images are being submitted to LPOD. While waiting for new images to appear I looked back to see what LPOD discussed 5 years ago today. It was a description of a long rille system circling around Promontorium Laplace, the eastern limb of the Jura Mountains. I first glimpsed the rille on an amateur image and found a good scan of Lunar Orbiter IV that revealed a significant rille that apparently had escaped notice. That was 5 years ago. Now we have LRO images of high resolution everywhere. The image today from the LRO QuickMap mosaic covers the same area as the earlier LO IV one. Look closely at each one (you will have to go to the QuickMap one and enlarge it more than here) and you will see some parts of the rille better on the 50 year LO image, and other parts more clearly on the LRO view. LO's advantages come from its lower lighting, revealing, for example, the continuation of the rille between points 1 and 2, shown on the earlier LPOD, that is nearly invisible on LRO. The better LRO resolution (on the zoomed view) shows more detail of the rille near where it is covered by the bright flank of Prom. Laplace near point 7. Presumably, the LRO camera team will release additional global mosaics with uniform lower lighting than in the QuickMap. Until that time, Lunar Orbiter and other ancient images will continue to be important. Of course, the LROC team knows that, which is why they have been digitizing Apollo images.

Chuck Wood

Related Links
Rükl plate 10
21st Century Atlas chart 19.

Yesterday's LPOD: More Than Crescent

Tomorrow's LPOD: Moon Bound or Earthbound?


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