High-Albedo inner slopes

High-Albedo inner slopes of young bowl shaped and cone shaped craters on the moon's near side

And the possible visibility of dim reflected light at the shadowed parts of those slopes

Description

Young bowl-shaped and cone-shaped lunar craters, such as Hipparchus C, Alfraganus C, Dollond E, or Kant P, show a remarkable High-Albedo value on their inner slopes. During Full Moon they look like bright spots or bright rings with somewhat darker floor. Due to their bright "white"-looking inner slopes, the shadowed parts of the interiors of these craters receive weak reflected light from the opposite sunlit parts. Hipparchus C is perhaps the most ideal example of lunar craters with dimly illuminated shadowed inner slopes.
  It should be possible to observe this effect (at Hipparchus C) through powerful telescopes, during the days following First Quarter Moon.
 Hipparchus C is the bright crater east-northeast of Hind, see Rukl's map 45.
 
 

Additional Information

The most convincing series of orbital photographs which show this sort of effect (at Hipparchus C') are Fairchild-photographs AS16-M-0165 to 0169 (made during the mission of Apollo 16 in april 1972).
  See also the third image of the LPOD Photo Gallery (on the MoonWiki's page Hipparchus).
  To investigate High Resolution close-ups of Apollo 16's Fairchild-photographs and to zoom in on them, it's very interesting to explore the APOLLO IMAGE ARCHIVE of the Arizona State University (ASU).
 
 List of Apollo 16's Fairchild Mapping/Metric photographs of Hipparchus C (the bowl shaped high-albedo crater of which the shadowed inner slopes could show us reflected light). Reseach Danny Caes
  - Revolution 17 Vertical AS16-M-165 to 169
  - Revolution 18 Vertical AS16-M-444 to 447
  - Revolution 25 Oblique Westward looking. AS16-M-568 to 573
  - Revolution 27 Oblique Northward looking. AS16-M-835 to 839 (AS16-M-837 shows Hipparchus C immediately below centre of photograph. A large part of this bright crater's eastern inner slopes and floor are shadowed, and the reflected light on them is easily recognizable).
  - Revolution 28 Vertical AS16-M-979 to 983
  - Revolution 29 Vertical AS16-M-1269 to 1273
  - Revolution 37 Oblique Northward looking. AS16-M-1399 to 1403 (as in AS16-M-837, AS16-M-1401 shows Hipparchus C immediately below centre of photograph. Although only a small part of the crater's eastern inner slope is shadowed, the reflected light is still recognizable).
  - Revolution 38 Vertical AS16-M-1663 to 1666
  - Revolution 39 Vertical AS16-M-1958 to 1962
  - Revolution 47 Vertical AS16-M-2184 to 2187
  - Revolution 60 Vertical AS16-M-2800 to 2804
  - Revolution 63 Vertical AS16-M-2956 to 2960
 
 List of Apollo 16's ITEK Panoramic photographs of Hipparchus C. Research Danny Caes
  - Revolution 18 Forward Facing Camera, AS16-P-4580/ 4582
  - Revolution 18 Aft Facing Camera, AS16-P-4585/ 4587
  - Revolution 38 Forward Facing Camera, AS16-P-4628 (only the sunlit western inner slope)
  - Revolution 38 Aft Facing Camera, AS16-P-4631/ 4633
  - Revolution 63 Forward Facing Camera, AS16-P-5348/ 5350
  - Revolution 63 Aft Facing Camera, AS16-P-5353/ 5355
  Note that all of the ITEKs photographs could be investigated at the Apollo Image Atlas of the Lunar and Planetary Institute.
 
 
 After all, it is not surprising that detail can occasionally be seen on the unilluminated portion, so much light is sometimes reflected from the surrounding sunlit cliffs or walls that Dr.W.H.Steavenson, using a shaded eyepiece, has seen the central mountains of the craters Agrippa and Godin when the interior of the crater was filled with shadow, and even noted the short shadow cast by the central mountains owing to the light reflected on to them by the cliffs.
 H.P.Wilkins, The Moon, P.18
 
 

List of bowl shaped and cone shaped craters with High-Albedo inner slopes on the moon's near side, compiled by Danny Caes

Abulfeda E
- Abulfeda E, a bright high-albedo craterlet west-southwest of Abulfeda itself, was captured on several frames of the southward-looking mapping/metric Fairchild camera of Apollo 16. The last ones of the series which show Abulfeda E have also captured the reflected light on the eastern shadowed inner slopes of that craterlet. The Arizona State University's zoomify-scan of frame AS16-M-0708 shows Abulfeda E very near the lower right corner of the photograph. The large crater in the foreground is Albategnius. To get a good view of the reflected light on Abulfeda E's shadowed eastern inner slopes, one should explore the maximum zoom of this craterlet!
Agatharchides A (Wilkins's Moore)
Alfraganus C
- The bowl-shaped high albedo crater Alfraganus C (west-southwest of Alfraganus itself) shows a degree of reflected light on the shadowed part of its eastern inner slopes, as captured on several of Apollo 16's northward-looking mapping/metric Fairchild frames, such as AS16-M-0831, in which Alfraganus C is noticeable just "below" the end of the SIM-bay's extended antenna (and Alfraganus itself just "above" of it).
Alpetragius B (Wilkins's Garcia Gomez)
Aratus
Beaumont D
Bellot (bright southern inner slope)
Bode
Bode A
Buch B
Byrgius A (Wilkins's La Paz)
Campanus A
Capella A
Capella D
Carmichael
Censorinus
Chladni
Cichus B
Cyrillus A
Cyrillus E
Cyrillus G
Darney
- Quite an amount of reflected light is visible on the shadowed eastern inner slopes of high-albedo crater Darney, as photographed by the mapping/metric Fairchild camera of Apollo 16. The best frame on which the effect of reflected light in Darney is noticeable, is AS16-M-2497 (zoomify-scan of the Arizona State University's Apollo Image Archive). In this frame, Darney's location is near the lower part of the right margin. Note also the reflected light on the shadowed slopes of Bullialdus's central peak system!
Descartes C
Dollond E
- Very bright reflected light is noticeable on the shadowed inner slopes of satellite crater Dollond E, which is the northern one of the pair of bright bowl shaped craters in the curious high-albedo region east of Dollond itself, once called Caramuelis by Van Langren. The southern one of the pair is Descartes C. Perhaps the best orbital photograph to explore the shadowed eastern inner slopes and flat floor of Dollond E is the Arizona State University's zoomify scan of Apollo 16's southward looking mapping/metric Fairchild camera frame AS16-M-0701, in which Dollond E was captured near the frame's upper right corner. While exploring this photograph, please zoom in at maximum on Dollond E itself! The amount of detail on the shadowed slopes is remarkable!
Dunthorne
Euclides
Fourier C
Gambart A
Gutenberg A
Hill
Hipparchus C (probably the brightest and best example of this sort of High-Albedo craters). LPOD Double Crossed (a weak trace of reflected light in Hipparchus C?)(Hippachus C is the bowl-shaped crater near the photograph's right margin).
Hipparchus G
Isidorus D (bright radial bands)
Kant P
Kies A (Wilkins's Lenham)(bright southern inner slope).
Kundt
Langrenus M
La Perouse A
Lassell D
Lehmann C
Letronne A
- Letronne A, a small high-albedo crater east-southeast of Letronne itself, is an interesting target to investigate reflected light on the shadowed eastern inner slopes of it (of this crater), this via orbital photographs made by Apollo 16's mapping/metric Fairchild camera.
- The Arizona State University's zoomify-scan of Fairchild frame AS16-M-2994 shows Letronne and also the small Letronne A near the frame's lower right corner, photographed during the local post sunrise hours. Note the reflected light on Letronne A's shadowed eastern inner slopes, after maximum zooming-in at this crater!
Linné
Mercator A
Mersenius C
Mosting A
- Mosting A, the well-known bowl shaped high-albedo crater south of Mosting itself, shows a remarkable degree of reflected light on the shadowed part of its eastern inner slopes, as seen in Apollo 16's northward looking mapping/metric Fairchild frame AS16-M-0849, in which Mosting A is noticeable at the upper right part of the photograph. See also AS16-M-1414 (and also at the frame's upper right part).
Nicolai A
North Ray Crater (near Apollo 16's landingsite).
Palmieri A
Pickering
Polybius A
Rhaeticus B
Small unnamed raycrater on the floor of Kant
South Ray Crater (near Apollo 16's landingsite).
Tralles A
Werner D

List of larger craters with High-Albedo inner slopes, on the moon's near side

Alfraganus
Aristarchus
- AS15-M-2611 is one of Apollo 15's oblique southward looking Fairchild photographs of Aristarchus and its shadowed eastern inner slopes. While zooming in on these shadowed slopes, note the twice reflected light on them! Research Danny Caes.
Dionysius
Lalande
- On the Arizona State University's (ASU's) zoomify-scans of Apollo 16's northward looking Fairchild magazines REV 27 and REV 37 it is possible to detect a certain degree of reflected light on Lalande's shadowed floor and eastern inner slopes.
Menelaus
- Several southward-looking frames made by Apollo 17's mapping/metric Fairchild camera show weak reflected light on the shadowed eastern inner slopes of high-albedo crater Menelaus. Perhaps the best frame to explore Menelaus's shadowed slopes is the Arizona State University's zoomify-scan of AS17-M-1667. In this frame, Menelaus was captured near the right margin. While exploring, please zoom in at maximum, to get a real close-up of Menelaus's shadowed (and vaguely illuminated) inner slopes!
Proclus
- AS17-M-0298 is one of Apollo 17's vertical photographs of the Proclus region, with Proclus itself near the photograph's lower right corner, near the out-of-focus part of CSM *America*. Note the reflected light on Proclus's inner shadowed eastern slopes! Research Danny Caes.

See also: List of lunar ray craters and bright (high-albedo) spots

Reflected light in FARSIDE craters with high-albedo inner slopes

- Craterlet at 9°30' North/ 170°20' West (northwest of Zhukovsky)
 AS16-M-0004 is perhaps the best example of an orbital photograph which shows reflected light inside a high albedo craterlet. Zoom in on the grey-looking craterlet inside the larger shadowed crater near the photograph's upper left corner, and observe that craterlet's "opposite illuminated" inner slope and floor!
  See also LAC 68 (page 136) in the Clementine Atlas of the Moon.
  Research Danny Caes.
  See also Stefan Lammel's experiment to enhance the reflected light in that crater and its surroundings, to show the remarkable effect of Shadows within Shadows!
  - Craterlet at the northeastern part of Dufay B's rim
 AS16-M-0033 is Apollo 16's photograph of reflected light inside Dufay B (Dufay B is the crater near the center of the photograph's left margin). It's very interesting to observe the small craterlet at Dufay B's northeastern rim, which shows much more twice-reflected light compared to the western inner slopes of Dufay B itself.
  See also LAC 68 (page 136) in the Clementine Atlas of the Moon.
  Research Danny Caes.
  - Triplet of craterlets at the western part of Papaleksi's rim
 AS16-M-0455 is one of Apollo 16's oblique west-looking photographs which captured very bright reflected light in the triplet of high-albedo craterlets near and at the western part of Papaleksi's rim.
  See also LAC 67 (page 134) in the Clementine Atlas of the Moon
  Research Danny Caes.
  - Paracelsus N
 AS15-M-0282 shows bright craterlet Paracelsus N near the photograph's left margin. In it (in Paracelsus N) there's noticeable reflected light on its western inner shadowed slopes.
  See also LAC 103 (page 206) in the Clementine Atlas of the Moon
  Research Danny Caes.
 
 

Far-side crater Lobachevskiy and its shadowed inner slope

Four of Apollo 16's orbital Hasselblad photographs show dim reflected light on Lobachevskiy's shadowed inner slope, revealing a curious low-albedo feature (a dark streak) on the slope.
 AS16-120-19274 (the first one of the four shows a little bit of dim reflected light on the shadowed inner slope).
 AS16-120-19275 (the second one of the four is slightly overexposed, and the dark feature is discernible on the shadowed inner slope).
 AS16-120-19276 (close up of the dark feature).
 AS16-120-19277 (overexposed close up of the dark feature).
  Research Danny Caes.
  Source photographs: Apollo Image Atlas, Lunar and Planetary Institute
 
 

Apollo 12, a shady craterlet, and a grey-tone calibration card

During the mission of Apollo 12 (november 1969) a grey-tone calibration card was photographed on the shadowed inner slope of a small craterlet. What could have been the source of illumination to make this calibration card visible? The craterlet's opposite sunlit inner slope? Or the white sunlit suit of the photographing astronaut?
  Anyway, take a look at :
 AS12-48-7040 (note the calibration card in the craterlet's shadow).
 AS12-48-7039 (close up of the craterlet's shadow with calibration card).
 AS12-48-7038 (close up of calibration card, note the visible regolith in the craterlet's shadow!).
 AS12-48-7037 (the calibration card as it was illuminated by the sun's light).
  Research Danny Caes.
  Source photographs: Project Apollo Archive, Kipp Teague/ Apollo Lunar Surface Journal, Eric M. Jones
 
 

Apollo 15 and the visibility of Silver Spur's shadowed western slope

During the mission of Apollo 15 (summer of 1971) a mountain south of the landingsite, called Silver Spur, was photographed with a 500-mm Hasselblad camera. The shadowed western slope of that mountain received dim reflected light.
 AS15-84-11250 (note the dim light on the shadowed slope of that mountain).
  Research Danny Caes.
  Source photograph: Project Apollo Archive, Kipp Teague/ Apollo Lunar Surface Journal, Eric M. Jones
 
 

The southwestern shadowed slope of Mount Hadley

Also during the mission of Apollo 15, CDR David Scott performed a Stand-Up EVA through the upper hatch of LM Falcon, to observe the surrounding landscape while it was illuminated by the lunar morning's grazing sunlight. One of those photographs shows Mount Hadley's shadowed southwestern slope while there's some dim reflected light shining onto it.
 AS15-87-11740 (note the dimly illuminated southwestern shadowed slope of Mount Hadley).
 AS15-86-11603 (here, in this well-known photograph which shows Jim Irwin and the LRV, the effect at Mount Hadley's shadow is much more recognizeable).
  Research Danny Caes.
  Source photograph: Project Apollo Archive, Kipp Teague/ Apollo Lunar Surface Journal, Eric M. Jones.
 
 

The Swann Range shortly after local sunrise

Note that almost all photographs of the Swann Range (the part of the Apennines immediately east of Apollo 15's landing site) show dim reflected light on their shadowed western slopes. Especially noticeable on the photographs made during the Stand-Up EVA of CDR David Scott (low sun and remarkable retro-reflection on the mountain's slopes!). Don't confuse with the disturbing reflected sunlight inside the Hasselblad camera's optical system! (a "grey cast").
  Research Danny Caes.
 
 

Bailly and the Dorfels (an interesting observation by Harold Hill)

In Harold Hill's splendid book A Portfolio of Lunar Drawings there's an interesting telescopic observation of a shadowed (yet dimly illuminated) mountain range at the moon's south-southwestern limb, a mountain range which was once called Montes Doerfel (or Dorfel). On page 131 of that book, Mr.Hill added a drawing of what he observed during the nocturnal morning hours of september the 27th, 1951. It shows the Dorfel range with five sunlit peaks, and the lower part of the Dorfel's mass in a dim light, of which Mr.Hill thought it could have been Earthshine (at that day in 1951, the moon was at its Waning Crescent phase, and, as seen from the moon, the Earth should have been at Waxing Gibbous).
  Now, could it (this weak illumination) have been a combination of Earthshine and reflected light of nearby sunlit slopes slightly east of the Dorfel range?
  Research Danny Caes.
 
 

LPOD Articles

Bibliography

- Ben Bussey and Paul Spudis: The Clementine Atlas of the Moon (Cambridge, 2004).
  - Hugh Percy Wilkins and Patrick Moore: The Moon.
  - All printed and online photographs of the moon, as seen through terrestrial telescopes and through the cameras of orbital spacecraft.
 

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