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The Lunar 100 list is from "Introducing the Lunar 100"
by Charles A. Wood (Sky &
Telescope, Sky Publishing Corp., April 2004,
Vol. 107, No. 4, pp. 113-120).
All rights remain with Sky Publishing Corp.
I (MSS) have transcribed this list for my personal use
and any errors are mine.
Unless stated otherwise, all photographs will be oriented such that north is up and lunar west to the left. |
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| 12 | Proclus | Oblique-impact rays | 16.1°N | 46.8°E | 28 km | Rükl 26 |
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02:00 UTC January 7, 2006
1/8 sec - f4.9 - ISO 100
3.0× telephoto
25.0 mm eyepiece with barlow (291.8×)
This is an average of eight color and eight B&W images. Before combining
the color with B&W, the red-green-blue components in the color image
were aligned. After combination, the contrast enhanced slightly and
an unsharp mask (3.0; 1.0; 0) was applied.
Proclus is the source of L12 (N18), its "oblique-impact rays". Note how the rays, the streaks of lighter material, radiate from Proclus to the north, east and south but not to the west. This implies something interesting happened here. The most likely cause is an asteroid striking at a very shallow, or oblique, angle from the southwest. But then why is the Proclus crater round and not elongated from the southwest to the northeast? Strangely enough, models indicate this is what should happen. The asteroid is moving so fast that the surface material at the point of impact can't get thrown out of the way. Instead, the energy of the impact heats the surface material which explodes outward creating a round crater. Only only on the periphery can the sufrace material be thrown out, preferentially "splashing" material away in the direction the asteroid was traveling.
| 25 | Messier and Messier A | Oblique ricochet-impact pair | 1.9°S | 47.6°E | 11 km | Rükl 48 |
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02:38 UTC April 1, 2004
1/4 sec - f4.9 - ISO 400
3.0× telephoto
12.5 mm eyepiece (300x)
Messier and Messier A are the small, white pair of craters, near the center of the picture, in Mare Foecunditatis with the pair of rays extending to the west-southwest. This is considered a ricochet-impact pair. The rays are brighter material lying under Mare Foecunditatis which was excavated by the impacts and preferentially scattered in one direction. And yes, these craters are named for Charles Messier, author of the famed Messier catalog of deep-sky objects.
| 40 | Janssen Rille | Rare example of a highland rille | 45.4°S | 39.3°E | 199 km | Rükl 67,68 |
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| 58 | Rheita Valley | Basin secondary-crater chain | 42.5°S | 51.5°E | 445 km | Rükl 68 |
01:12 UTC April 15, 2005
1/15 sec - f4.9 - ISO 400
3.0× telephoto
12.0 mm eyepiece (312x)
This is an average of two images with
an unsharp mask (5.0; 0.5; 0) applied.
Janssen Rille lies in Janssen
crater. The illumination is not optimal
here but one can just make out the valley extending northward and
slightly west of the central peak of the crater, then looping back
to the east towards the smaller overlapping crater, Fabricius.
To the northeast is Rheita Valley. Not a valley as we normally
think of it, Rheita is actually believed to
be a chain of closely spaced, overlapping craters.
| 96 | Leibnitz Mountains | Rim of South Pole-Aitken basin | 85.0°S | 30.0°E | Rükl 73,V |
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Leibnitz Mountains