February 15, 2018
Originally published September 7, 2008
image by Christian Viladrich, France
High resolution (HR) is a term with a shifting meaning. Ever since the historic Lick Observatory photos of the 1930s and 40s, HR probably corresponded to 2-3 km. The best plates of the Consolidated Lunar Atlas of 1967 pushed the definition of HR to about a kilometer, where it stayed until amateur imaging of the last year or two has reached to 600-800 m. I haven't measured the resolution of Christian's excellent image of the Stofler area of the southern highlands, but there are more craters on the floor of Stofler than on any previous Earth-based images I've seen of it. Besides bragging rights, what good is higher resolution? The main thing it does is show smaller craters, and since the number of craters roughly follows an inverse square law: cut the diameter of craters in half and approximately twice as many exist. Many of these smaller craters are in lines or clumped together - they are secondaries. If you can separate the secondaries from the primaries, better resolution allows age determinations based on crater counting of small areas. Spacecraft images have had resolutions of 100 m to 1 m, and next year the Lunar Reconnaissance Orbiter will achieve 0.5 m resolution.
22 August 2008. Celestron 14 at F/19 + Skynyx 2.1M video camera + red filter; exposure time: 17 ms, gain: 10, 600 stacked image; processed with Iris software with distorsion correction.
Rükl plate 65
Christian's lunar closeups
Yesterday's LPOD: Introducing Kimura
Tomorrow's LPOD: A Bigger, Older Clavius?