Pronounced Central Peaks

Pronounced Central Peaks

(special features list)

Description

This is a list of lunar craters with unusually large central peaks in relation to the diameters of the craters. Many of these pronounced central peaks look curiously "globular"-shaped. The most well-known example is the so-called Egg-In-A-Nest in Alpetragius (AS16-119-19057 is one in the series of Apollo 16's orbital Hasselblads showing Alpetragius's Egg-In-A-Nest). Other central peaks are prominent because they are tall in relation to the crater depth, or through a combination of diameter and height.
 
 

Additional Information

Note: the following lists indicate some representative craters in each class. They are by no means comprehensive. That is, there are likely to be many craters on the Moon with central peak ratios larger than some of those listed.

Broad Peaks

Craters whose central peaks are large in relation to the crater diameter:

Name	Peak Diam.	Crater Diam.	Ratio	Notes
Alpetragius	16	41	0.39
Römer	13	41	0.32
Icarus	27	95	0.28	on the moon's far side
Lockyer G	6	24	0.25	west-northwest of Lockyer
Thebit L	2.7	11	0.25	west-northwest of Thebit and Thebit A

• • The diameters are in kilometers, and "Ratio" is the estimated diameter of the central peak divided by the diameter of the crater. The diameters of many initially broad central peaks may have been diminished by subsequent flooding or in-fill of the crater floors (which leaves only the tallest part visible).
  • In addition to craters with isolated hemispherical peaks, there are craters in which the entire floor is more convex than the general curvature of the Moon. The convexity of these domed floors is usually slight, and difficult to verify.
  • Not all central peaks may be formed by rebound at the moment impact. In some cases the mounds of material seen on the floor may arise from slumping of the walls. Thebit L and Römer may be in this category.

Tall Peaks

Craters whose central peaks are tall in relation to the crater depth:

Name	Peak Height	Rim Height	Ratio	Notes
Doppelmayer	1.3	1.3 to 0	1.00	peak taller than nearly all of rim; crater tilted and breached
Icarus	4.1	4.7	0.87	on the moon's far side
Taruntius	0.9	1.1	0.82
Theophilus	3.0	4.1	0.73
Albategnius	1.7	3.2	0.53
Capella	1.8	3.5	0.51
Tycho	2.4	7.7	0.51
Alpetragius	1.7	3.9	0.44	rim height 2.7 km on west
Haldane	0.35	0.8	0.44	peak higher than parts of rim
Warner	0.2	0.5	0.40	peak higher than much of rim
Römer	2.0	5.5	0.36
Copernicus	1.4	3.8	0.36

• • Peak Height and Rim Height (crater depth) are in kilometers. The height of the central peak is estimated relative to the general floor. The "Rim Height" is an estimate of the height of the highest point on the rim with respect to the same reference on the floor (this is sometimes called "crater depth" and should not be confused with the more usual "rim height" measured with respect to the terrain outside the crater). "Ratio" is the Central Peak Height divided by the Rim Height. A Ratio greater than one indicates the peak is taller than any point on the rim; but the ratio can be highly distorted from its original value if the crater floor has filled in by slumping or flooding.
  • "Crater depth" is sometimes expressed as an average height of the rim above the general level of the floor, rather than the maximum value ("Rim Height") estimated here. The difference can be substantial. For example, the rim of Römer appears to be about 5.5 km above the floor on the west, but only 4.2 km on the east. The rim of Thebit L may be 1.3 km above the floor on the east, but only 0.5 km on the west. And so on.
  • The table includes the craters with the highest ratios selected from a list by Kurt Fisher of craters whose central peak heights can be measured on NASA LTO charts. Since the vast majority of craters were not plotted on LTO's, many examples with higher ratios may exist.
  • Many of the examples of what were originally likely to have been craters with extremely tall and massive central peaks seem to be found among ones that are now flooded, so that only the highest parts of the peak and rim remain visible. Doppelmayer is an example, and it is possibly unique in that the top of the central peak may be higher above the mean lunar surface than any surviving point on the rim.
  • Aside from Doppelmayer, the only other crater that has a peak that may be higher than any part of its rim seems to be Icarus, although the shadow measurements don't seem to support this impression (which comes from oblique photos).

• There's a curious abundance of craters with central peaks at the Arzachel-La Caille-Parrot region. It's remarkable to see so many central peaks up here, such as those at the curved row of craters Argelander, Airy, Donati, Faye, and also in craters Parrot C, Arzachel, and Alpetragius (to the west). See chart 55 in Antonin Rukl's Atlas of the Moon, charts 82 and 83 in the Times Atlas of the Moon, charts 13 and 16 in the 21st Century Atlas of the Moon. Research: Danny Caes

• Some craters on the moon's surface have central peaks which look deceptively "earthlike" (they look like geologically young mountains on earth). One example of such an "earthmountain-like" central peak is the one on the dark floor of farside crater Tsiolkovskiy (looking like an "isle of chalk, surrounded by a sea of asphalt"). Research: Danny Caes
• Another (somewhat) "earthlike" system of mountains is the central peak cluster of farside crater Jackson, see LPOD Mystery peaks of the Moon.
• Other lunar craters with pronounced central peaks: Bok, Behaim, De Forest (De Forest's pronounced central peak is very well depicted on LAC 142 in The Clementine atlas of the Moon), De Vries, Lilius (see LAC 126). Research: Danny Caes
• 0° East/ 82° South could be the location of a pronounced central peak surrounded by the northern half of a crater's rim. This peak and its adjacent "northern arc" are depicted at the centre of Part M in the alphabetically arranged radar map of the moon's southpole region. Research: Danny Caes

LPOD Articles

Hemispherical Peak (Lockyer G).
Pole 2.0 (a possible pronounced central peak at 0° East/ 82° South?)(surrounded by the curved northern half of a crater's rim?) Research: Danny Caes
A Really Tall Peak (Icarus).
Big Bounce (Icarus).
Peaks and Walls (Alpetragius/ Arzachel/ Parrot C).

Bibliography

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