Twin craters

Twin craters, couples, doublets, and triplets

Table of Contents

[#Twin craters, couples, doublets, and triplets Twin craters, couples, doublets, and triplets]

[#Twin craters, couples, doublets, and triplets-Description Description]

[#Twin craters, couples, doublets, and triplets-Overview of interesting couples and triplets Overview of interesting couples and triplets]

[#Simultaneous Impact Twins Simultaneous Impact Twins]

[#Simultaneous Impact Twins-LPOD Articles LPOD Articles]

[#Simultaneous Impact Twins-Bibliography Bibliography]

Description

Telescopic observers of the moon have noticed them since selenography's early days: twin craters. Some of these twins are very pronounced and don't require very powerful telescopes. A typical example: [/Cardanus Cardanus] + [/Krafft Krafft] in the western part of [/Oceanus%20Procellarum Oceanus Procellarum]. Most of the lunar surface's twin craters are too small to observe through common telescopes, such as the unnamed couple of bowl-shaped craterlets just west of the [/Fresnel%20Ridge Fresnel Ridge] (Hill 305) near Apollo 15's landing site.
  There are triplets too, such as the well-organized trio on the floor of [/Endymion Endymion].
  The list below is an overview of well-known and unknown twins, couples, doublets, and triplets (to observe through binoculars and telescopes) (small, common, and powerful telescopes).
 
  Note that the word "twin", as used here, means only that a pair of nearby craters is similar in size and appearance. It does not necessarily imply that they were born at the same moment. But some - such as Ariadaeus and its A were. Simultaneous impacts can be identified by a slightly curved ridge (septum) occurring where the two rims touch. For craters that do not touch it is difficult to determine if they were formed together.
 
 

Overview of interesting couples and triplets

• [/Beer Beer] and [/Feuill%C3%A9e Feuillée]. A well-known pair. An unnamed catena runs east-southeast of Beer, which is an interesting test-object for common and powerful telescopes. Frequently photographed during the mission of Apollo 15 (orbital photography).
• [/Cardanus Cardanus] and [/Krafft Krafft]. A well-known pair in the western part of [/Oceanus%20Procellarum Oceanus Procellarum]. Both craters are connected to each other via [/Catena%20Krafft Catena Krafft]. The two craters are observable through common telescopes, the connecting catena through powerful telescopes.
• [/Carmichael Carmichael] and [/Hill Hill], near [/Sinus%20Amoris Sinus Amoris]. An interesting pair for small and common telescopes.
• Doppelmayer J, K, and L. A trio in the centre of Mare Humorum. Observable through common telescopes.
• [/Draper Draper] and [/Draper Draper] C, in [/Mare%20Imbrium Mare Imbrium] near the [/Montes%20Carpatus Montes Carpatus]. Observable through common telescopes.
• Triplet (row of three craterlets) on the floor of [/Endymion Endymion]. Discovered by [/P.%20B.%20Molesworth Major Molesworth] (1894); see page 159 of T.W.Webb's [/Celestial%20Objects%20for%20Common%20Telescopes Celestial Objects for Common Telescopes], Volume One; The Solar System. A curiosity, to observe through powerful telescopes!
• [/Eratosthenes Eratosthenes] A and B (south of [/Wallace Wallace]). A powerful telescope is required.
• Fra Mauro H and HA* Slight overlap but somewhat old so can't tell if there was a septum; however H is considerably fresher than HA so probably not simultaneous formation.
• Fontenelle C + F, which look somewhat like the keyhole-shaped Fauth, although both craterlets (Fontenelle C and F) were depicted as two separate craters on Rukl's chart 3.
• Hercules J and K, which is a neat pair; observable through common telescopes.
• The unnamed pair of bowl-shaped craterlets west of Hill 305/ [/Fresnel%20Ridge Fresnel Ridge]. See: AS15-P-9804 (right half of the photographic strip). This is a VERY interesting pair to test your telescope's optics (if it's possible to split the pair into two craterlets, then your telescope is O.K.!). A powerful telescope is required.
• The unnamed pair of craterlets on the floor of Kies, which is also an interesting test-object!
• Galle B and BA, north of Aristoteles. Ideal for common and powerful telescopes.
• Democritus B and BA, southwest of Lamech's Danjon (which is the incomplete formation between Kane and Gartner).
• The unnamed pair of craterlets northwest of Pytheas (at 21°50' North/ 22°15' West). This is a very good test-object! Nearby this pair, there's an interesting cluster of craterlets (at 21°10' North/ 22° West). In this region (around Pytheas) there are lots of secondary craterlet-chains, related to the formation of the large crater Copernicus.
• The well-known couple of craterlets [/Plato%20Craterlets on the floor of Plato]. This is probably the most observed one of the small couples. Sometimes it's as if this couple is "not there", and because of this strange "absence", lots of articles were written, to describe the "disappearance" of Plato's couple! (see also the LPOD of April the 14th, 2008: a spectacular orbital Kaguya photograph of Plato!).
• [/Gambart Gambart] B and C. Observable through common telescopes. Gambart C was once called Moreux by F.C.Lamech.
• [/Helicon Helicon] and [/Le%20Verrier Le Verrier]. A well-known pair in [/Mare%20Imbrium Mare Imbrium], near [/Sinus%20Iridum Sinus Iridum]. Observable through small telescopes and binoculars.
• Lichtenberg AA and anon, at 29° North/ 63°20' West. Common to powerful telescopes are required.
• The isosceles triangle (triplet) east-southeast of [/Markov Markov]. A curiosity, to observe through powerful telescopes!
• [/Messier Messier] and [/Messier%20A Messier A] (formerly known as W.H. Pickering). The most well-known pair on the lunar surface. Not exactly a twin, because one of the two is elliptical. The Messiers were frequently photographed during the Apollo program (orbital photography).
• [/Secchi Secchi] A and B (both captured on Lunar Orbiter 2's Frame 2024).
• [/Ritter Ritter] and [/Sabine Sabine], at [/Mare%20Tranquillitatis Mare Tranquillitatis]'s southwestern rim. An interesting pair for small and common telescopes.
• [/Ritter Ritter] B and C. These are two bowl-shaped craters just north of Ritter. In between these two, there's a small craterlet which is a fine object to test the optics of your telescope! (source: the dedicated Belgian moon-connoisseur Antoine van der Jeugt).
• [/Smithson Smithson] (formerly [/Taruntius Taruntius] N) and [/Taruntius Taruntius] O, in northeastern [/Mare%20Fecunditatis Mare Fecunditatis] ([/Sinus%20Successus Sinus Successus]). Observable through common and large telescopes.
• [/Taruntius Taruntius] K and P, at Dorsum Cayeux. Observable through common telescopes.
• [/Sirsalis Sirsalis] and [/Sirsalis Sirsalis] A (Sirsalis A was once called Bertaud by H.P.Wilkins). Observable through common telescopes.
• [/Steinheil Steinheil] and [/Watt Watt]. A well-known pair near [/Mare%20Australe Mare Australe]. Observable through common telescopes.
• [/Strabo Strabo]'s triplet ([/Strabo Strabo] L, B, and N). Observable through common telescopes.
• [/Theon%20Junior Theon Junior] and [/Theon%20Senior Theon Senior], southwest of [/Mare%20Tranquillitatis Mare Tranquillitatis]. An interesting pair of bowl-shaped craters, for small and common telescopes.

Simultaneous Impact Twins

• Ariadaeus and A. Simultaneous formation
• Simultaneous impact? doublet SE of [/de%20Gasparis de Gasparis]. Yes. DeGasparis E and F.
• Triplet east of [/Encke Encke] (with Encke M in it). At least two craterlets of this triplet are simultaneous impacts. A common or powerful telescope is required to split the row into three craterlets!
• Doublet and triplet in [/Landau Landau] - simultaneous or secondaries?
• Plato K & KA
• North of Moro Dome on this Apollo 15 image
• South rim of Boyle three touching craters, two with straight wall between them.

LPOD Articles

A Formation of Surprise

Bibliography

A.J.M.Wanders, Op Ontdekking in het Maanland (Het Spectrum, 1949).
 

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This page has been edited 1 times. The last modification was made by - tychocrater tychocrater on Jun 13, 2009 3:24 pm