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The Classic Moon

beginner classic moon refractor
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#51 AllanDystrup

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Posted 07 April 2016 - 03:28 AM

Starry nights are a limited ressource up here in N. temperate Europe, and so I've not had the chance to spend as much time on the moon, as I'd like to. I did however manage to do an overview study of my favourite region on the moon: the Aristarchus Plateau, and so here's my report from that night in late January this year (2016).

 

 

Aristarchus Plateau
Procellarum NW, 11 dy

    

     It’s late January 2016, 22h local time. There’s a 11 day waxing gibbous (83% illum.) moon hanging high up (ca. 50° alt.) almost due south, on the border between Orion and Gemini. The weather is calm and freezing (-10°C/14°F) with above medium transparency and seeing, and after 20 minutes under the stars my Vixen FL-80S doublet refractor has now fully adapted to the >25°C temperature drop from the warm room inside our house.  There’s is no wind, and so it doesn’t feel too cold to make a drawing, but my breath is condensing and freezing on the eyepiece turret, so I have to breathe gently out the corner of my mouth…

    
     I point my small refractor at the Moon, centering the view at Aristarchus and the surrounding plateau in the NW part of the great Procellarum Basin. This is one of the most geologically diverse areas on the near side of the Moon, with records of lunar history from the ancient pre-Imbrian (>3.8 BY) up to the youngest Copernican epoch (<1 BY).

    
     The Imbrium basin impact (3.9 BY) threw up a 4km thick layer of ejecta on top of the surrounding rims and caused a series of linear (radial as well as concentric) tectonic segmentations and faults, including the subsequent 2km uprising of the 170x200 km, diamond-shaped Aristarchus Plateau. The following Orientale basin impact plus the large Herodotus and Prinz craters (all lower Imbrium: ~3.8 BY) further coated the plateau with primary ejecta and secondary craters (thus reseting the crater-age clock of the plateau).

    
     The oldest mare lava extrusions (3.6 BY upper Imbrian
red Teleman lava) is found along the extensive faults at the plateaus NW (“Agricola Straits”) and E borders; This early flooding was accompanied by pyroclastic vulcanic eruptions, that coated the plateau and surroundings with a 10-20m deep red iron-rich glassy fine-grained ash : Dark Mantle Deposit (DMD).

    

     Later highly fluid lava (2.7 BY old Eratosthenian dark blue Sharp lava) was erupted from many rimless cobra-head vents, from which they eroded narrow channels down-gradient, including the largest sinuous rille on the Moon, Schröter’s Valley on the plateu (11 km wide and almost ½ km deep, running downslope 160 km to the NE). The erupted lava flooded the Plateau surroundings including the floors of the afore mentioned large impact craters (Herodotus and Prinz).

    
     Aristarchus
is a very young (175 MY), 42km wide and 3km deep impact crater from the Copernican epoch (<1 BY); It is sharply defined with a well-developed terassed inner wall, very bright with a high reflectivity caused by underlying anorthositic highland rocks, that has been excavated by the deep impact (Aristarchus is easily spotted in in my 8x30 bino).

    

     There are a lot of smaller geologic features visible under favourable conditions, and with larger telescopes :  the dark bands in the western crater wall of Aristarchus, the small cobra head vents and rilles in the Montes Harbinger region, the sinous rilles Rimae Aristarchus to the NW of the plateau,  the steep mare ridge edge Rupes Toscanelli, the lunar dome Herodotus Omega just S of Herodotus, the Dorsum Niggli running from the Mts. Agricola across the Agricola Straits to the Aristarchus Plateau, the bright ejecta rays from crater Aristarchus, and much more.

    
I consider this an overview study of the area, and am looking much forward to future detail studies with my small refractors.

    

AP.png

 

Here's a ->link to the OBS. Report<-, with more details.

 

Allan    


Edited by AllanDystrup, 07 April 2016 - 04:16 AM.

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#52 Sasa

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Posted 07 April 2016 - 03:47 AM

Allan, very nice and interesting observation and write up, thanks. This is favorite region of mine as well (and I guess that not only mine). I even tried to sketch it several times, but the complexity is to high and I was never satisfied with the result. I have at least one sketch of crater Prinz and Montes Harbinger from 2 years ago:

 

Moon_20130619_MontesHerbinger.jpg


Edited by Sasa, 07 April 2016 - 04:19 AM.

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#53 Organic Astrochemist

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Posted 07 April 2016 - 08:30 PM

What a wonderful thread.
Thanks to Allan for starting it and to all who have contributed.
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#54 AllanDystrup

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Posted 15 January 2019 - 08:08 AM

.

E Imbrium, Apollo 15

    

    

     It’s a fresh and windy early evening in mid-January (2019-01-14, 19:00 Loc. CEST, UT+1). We’re experiencing the third low pressure from NW here in January, now sweeping across Denmark with stormy winds, so the start of this year has certainly not offered the best conditions for astronomical observations; -- but the half moon is now sailing high up at 46⁰ in Taurus close to the meridian, and after some weeks with rain and overcast skies, I now seize the opportunity to have a look at our satellite.

 

     I mount my trusty classic Vixen FL-80S/640mm refractor on a sturdy Zeiss Ib EQ tripod, and though both transparency and seeing tonight are well below medium, and strong winds are huffing and puffing at my OTA, observation is still quite satisfactory, in between the wavering seeing and gusting wind.

 

     I load a TV 8mm Ethos in the turret, yielding a mag. of 120x in a good 25’ FOV. I settle on the eastern Mare Imbrium region as my target, focusing on the area SE of Archimedes, which held enough interest from a Lunar geological point of view to be selected as landing site for the Apollo 15 mission. The terminator tonight is located in a line just W of Plato down to Eratosthenes, with beautiful shadows from the E rim of these craters flooding half of the crater floors. To the SE of Eratosthenes are seen some of the DMDs (Dark Mantle Deposits) that were created by volcanic activity in the wake of the Imbrium crater impact.

 

     The landing site for Apollo 15 was selected to be on the lava flows of Palus Putredinis at the W base of Mt. Hadley in the Apennine Mt. range, close to a 1km wide lava channel (the Hadley Rille), -- which I however am not able to spot tonight. Apollo 15 returned samples of impact-shocked rock and lavas from the site, that made it possible to date the formation of the Imbrium basin as well as the mare lavas.
  
     The W side of the Apennines rise up steeply to 5 km high scarps, then slopes down towards the SE. The mountain range was created when Lunar crust at the edge of the Imbrium basin was warped up by the impact, and then coated by an ejection blanket excavated down to 60 km depth. To the W of the Apennine scarps, landslide blocks have slid down from the basin rim and formed slump terraces. The Spitzbergen mountains and the light hued hilly terrain S of Archimedes (the Apennine Bench) are old igneous rocks erupted 3.8 Byr ago shortly after the Imbrium impact.

 

     Later, around 3.3 Byr ago, radioactive heating in the Lunar mantle generated the lavas that flooded the Imbrium basin, apart from high crater rims (like Archimedes), the top of some igneous rock formations on the crater floor (like Spitzbergen and the Apennine Bench) plus terraces at the basin rim now protruding as thin ridges and rocky crests.

    

A15-01.jpg
A15-02.jpg

     Snapshot by iPhone5
          *click*

 

     -- Allan


Edited by AllanDystrup, 15 January 2019 - 08:50 AM.

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#55 AllanDystrup

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Posted 03 December 2019 - 04:09 AM

.

The Moon, age ~4 days.

    

    
     It’s an early evening at the end of November (2019-11-30, 17:30 local). This has been the most overcast and wettest November month (as indeed the whole autumn season) in Danish meteorological history, -- i.e. in the past 150 years since systematic recordings started the mid 1800 century. Last time we had clear skies was a month ago (2019-10-28), so climate change is indeed unfolding here in Europe. frown.gif

    
     I have embarked on a small Moon project with the aim of studying and understanding the main lunar landforms, i.e. observing the geomorphological and geological units on the (nearside) lunar surface, as observable from my suburban backyard using a modest 7” telescope. I’m observing visually, and documenting my observations by taking smartphone snapshots along the way. Neither telescope (a 1990 vintage “classic” Maksutov) nor camera (iPhone) are of perfect or even excellent optical quality for this purpose, but both are quite good, and so -- as we used to say when I worked in test automation and QA of software development --, “when the error rate goes below your set and measured quality level: SHIP IT!”. smile.gif  That said, I consider myself a beginner also in this area, so any corrections and supplemental information will be most welcome.

    
     The Moon tonight is a waxing crescent, the lunation is around 4 days (4.1dy age, 18.2% illumination), and the longitudinal libration is close to 4½°, which is favorable for observing the Maria peeking out from the lunar far side at the E limb. The temperature is around the freezing point (0°C), and the humidity is relatively low (85%). The transparency and seeing are both just above medium with some atmospheric wavering, as I’m passing from astronomical dusk into proper night with a suburban/rural transition NELM of ~6.4.

    

    
     The 4-day moon is dominated by the central, old pre-Nectarian impact basin of Mare Fecunditatis and the younger Nectarian multi-ring basin of Mare Crisium. M. Crisium is surrounded by several Nectarian craters that – like the basin itself -- has been flooded and filled by basalt in the upper Imbrian epoch, notably: Cleomedes, Condorcet, Neper, Firmicus, Dubyago, Apollonius. Of the Maria at the E limb, Marginis, Smythii and Australe are all pre-Nectarian, while Humboldtianum is Nectarian (same as M. Crisium). The lava fill of the limb-Maria took place mostly in upper Imbrian, as was indeed the case for the other major impact basins on the Moon (apart from central Imbrium-Procellarum, which were also lava flooded later, in the Eratosthenian period).

 

     The northern highland of the 4-day crescent moon is dominated by several old pre-Nectarian craters (De La Rue, Endymion), while some younger, lower Imbrium craters decorate the southern highland: Petavius and Furnerius. A pair of really young craters are found at the E border of M Fecunditatis: the Eratosthenian Langrenus and the Copernican Taruntius.

    
     In the table below I have categorized the main geology formations on the ~4dy crescent Moon (graphic from Wikipedia):

 

Moon 4Day Overview - Calender.jpg
    

Moon 4Day Overview - IMG.jpg
*click*

    

     -- Allan

 

 

 


Edited by AllanDystrup, 03 December 2019 - 04:23 AM.

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#56 AllanDystrup

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Posted 04 December 2019 - 06:32 AM

.

Mare Crisium area, 4-day moon.

    

    

     The Crisium Basin was created by a low-angle oblique impact of an asteroid coming in from the west, back in the late Nectarian period (3.84 Billion years ago); The impact created an elliptic W-E elongated multi-ring system, with a massive main basin ring (#2: Crisium) surrounded by two lower outer rings: one passing just S of Cleomedes (#3) and the outermost passing S of Geminus (#4).

    
     Later, in the upper Imbrian epoch (~3 Byr ago), lava penetrated from the lunar mantle up through fractures in the impact site and flooded the central basin (Mare Crisium) as well as low areas between the rings #2 and #3 (Mare Anguis, Mare Undarum). Nectarian lava also flooded some nearby Nectarian craters, notably: Cleomedes, Condorcet, Firmicus, Apollonius and Dubyago, all of which now show relatively smooth and dark crater floors. Note that the ancient basins further E towards the moon limb (the pre-Nectarian Marginis and Smythii) and also the large Nectarian craters Neper and Goddard were also flooded by lava in this lunar epoch.

    

     The lava in the Crisium basin has formed a relatively smooth dark plain. All along the inside of the main crater ring (#2) is seen a shelf/bench of lava covering the inner sloping terrace of the ring; After the first lava flood, the crust below the central lava plain subsided (~200m down), but after a secondary flooding, lava has pushed up against the basin bench forming the inner “wrinkle ridge” ring (#1). A pair of early Imbrian craters (Yerkes, Lick) have been partly submerged by this lava at the far SW edge, and a row of three younger Eratosthenian craters (Picard, Pierce, Swift) have since excavated some early, deeper and darker lava at the W side of the Mare.

    
     Just E of M. Crisium can be seen some patches of dark mare looking somewhat like the Chesire Cat smile (Charles Wood has christened this formation: “Lacus Risus Felis”, aka the Cat’s Smile Lake...). Further E still is M. Marginis with a lava filled crater to the S (Neper) and another one to the N (Goddard); At the northern rim of Goddard is a bright patch, -- a swirl (like Reiner Gamma in Oceanus Procellarum) extending from the far side of the Moon.

    

4dy - Crisium Center.jpg
*click*

    

     -- Allan


Edited by AllanDystrup, 04 December 2019 - 02:35 PM.

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#57 AllanDystrup

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Posted 05 December 2019 - 02:13 AM

.

4-day moon, NE Limb (Cleomedes-Endymion).

    

    

     The NE part of the 4-day moon is dominated by the pair of large pre-Nectarian craters: De La Rue and Endymion to the N, and by a row of three craters: Messala (pre-Nectarian), Cleomedes (Nectarian) and Geminus (Eratosthenian) towards the S.

    
     Cleomedes is a 125km wide crater with a smooth floor from lava that has covered all but the tip of the central peak in the basin; Five smaller impacts have since (in the Imbrian-Copernican period) pitted the lava floor, the smallest being Cleomedes J (12km diameter), which I can *just* glimpse in the mediocre seeing tonight. The central part of the lava fill has been pushed up by the lava below, giving rise (literally) to several arcuate fractures/rimae (which I cannot see tonight, -- and they are probably beyond reach on any night for my 7” instrument).

     
     Between Endymion and Messala is a group of relatively smooth lava plains, including Lacus Temporis and Lacus Spei. Charles Wood speculates that these dark smooth patches may indicate a “crypto mare”, where an ancient dark lava plain has been mostly covered by later impact craters with their rays and ejecta carpets. If so it would be like the ancient Mare Australe, but even more impact-pummeled and covered by lunar crust regolith.

    

     East of Endymion, towards the lunar limb, I can see the almost edge-on multi-ring lava-filled impact basin: Humboldtianum, including its outer ring (#2) close to the E rim of Endymion, and the inner ring (#1) surrounding the dark mare lava.

    

Moon 4dy NE.jpg
*click*

    

     -- Allan


Edited by AllanDystrup, 05 December 2019 - 11:15 AM.

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#58 AllanDystrup

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Posted 06 December 2019 - 03:09 AM

.

4-day moon, SE Limb (Langrenus-Petavius).

    

    
      The SE limb of the 4-day moon is a heavily cratered highland with few mare plains. The largest plain is the E part of the pre-Nectarian Fecunditatis lava-covered basin, featuring a couple of wrinkle ridge dorsae (Morson and Andrusov), a triplet of small Imbrian craters plus two large craters at the far E side of the basin: the pre-Nectarian Vendelinus and the Eratosthenian Langrenus. Two far-side pre-Nectarian impact basins, each with its Nectarian mare, are also extending over the eastern lunar limb: Mare Smythii to the N and Mare Australe towards the S.

    
     M. Smythii is contained within a multiring basin (like M. Crisium): the inner ring (#1) obviously surrounds the mare proper, and the outer ring (#2) can be glimpsed (imagined?), enclosing the craters Gilbert and Kästner. A dark, partly submerged crater: Kiess at the S end of M. Smythii can also be identified close to the lunar limb. As apparent from Lunar Reconnaissance Orbiter (LRO) photographs, the Australe basin is of ancient pre-Nectarian origin without any significant ring or ejecta structures, but mostly appearing as a circular assemblage of many old lava-filled craters, a couple of which (Oken, Lyot) can *just* be spotted (literally) as dark patches on the SE lunar limb.

    
     A dominant feature in the SE highlands of the 4-day moon is the radial sculpture of the Snellius and Rheita Valleys, -- crater chains formed by ejecta from the nearby Nectaris Basin impact. On either side of the Snellius Valley is a large crater: the young Lower-Imbrian Petavius to the N, and old pre-Nectarian Furnerius to the S. Petavius has thrown a splendid ejecta carpet up into southern M. Fecunditatis, and I can glimpse the floor fracturing in the crater (Rimae Petavius) caused by uprising magma from below.

    

MOON 6dy SE.jpg
*click*

    

     -- Allan


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#59 AllanDystrup

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Posted 09 December 2019 - 01:36 AM

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The Moon, age ~6 days.

    

         
     It’s late afternoon in the start of December (2019-12-02, 17:00), and I’m out in the astronomical dusk to catch the 5.9 days waxing crescent moon (35% illuminated) hanging low in the south, at almost 16° altitude in Capricorn. The temperature is at the freezing point (0°C) with a medium humidity (80%), and the dew point down at -2°C. The LP is a good suburban/rural transition NELM 6.5 (SQM 20.9), but the transparency is varying fast 2-4/7 due to low incoming stratus fractus clouds. The seeing is just above medium (6-7/10), but somewhat hampered by a steady wind that gives rise to a rather shimmering image. I’ve set up my telescope for a full disc view of the Moon at 86x magnification in a 1.2° FOV, but I have to make my observation quick and short tonight, as our oldest son will be dropping off our youngest grandchild within an hour, -- where after the Moon will have to take care of itself...

    
     The terminator area of the 6-day Moon is dominated by several large, lava filled basins; On the N hemisphere I can detect two remnants of the outermost part of the oldest pre-Nectarian basin Procellarum (aka Gargantuum): the Vitruvius Ring segment of mountain massifs arching up towards the N, as well as its presumed continuation encircling the mare-filled trough known as the eastern part of Mare Frigoris; Below Frigoris, Serenitatis was created by a pair of Nectarian impacts that formed a large southern basin (now holding Mare Serenitatis) plus a smaller northern basin (with Lacus Somnorium). On the S hemisphere, the oldest and evidently subdued basins are the pre-Nectarian Tranquillitatis and Fecunditatis, now partly overlaid by the younger and splendid, multi-ring Nectarian-period (sic...) basin Nectaris.

    

    

     Starting from the N, Mare Frigoris reaches, in an arcuate line, from west above Plato on the outer Imbrium basin ring (now E of the terminator), to the far east bordering on the crater pair Hercules and Atlas. Frigoris is part of a depressed lava-filled zone around the Imbrium basin, but inside the excavation boundary of the Procellarum basin, which is marked by the arcuate Vetruvius Front to the E of the Serenitatis basin. The South Serenitatis basin is bounded by the outer Taurus-Littrow ring (#2), but it also features an inner Wrinkle ridge ring (#1) in the mare lava, which to the E is marked by the long Serpentine Ridge. Serenitatis is of a relatively young Nectarian age, as can be seen by secondary craters from its basin ejecta being superposed on the Crisium structure (early Nectarian).

    

     The large crater Posidonius at the NE shore of M. Serenitatis shows an interesting lava-filled, uplifted and fractured floor with a rille system (Rimae Posidonius) and a prominent landslide ridge. Other interesting structures in this area are the partly lava-flooded crater Le Monnier and the Taurus-Littrow mountain complex N of Vetruvius, where Apollo 17 landed; – these deserve higher magnification studies, but I must postpone that for a later observation.

    

Moon 6DY N.jpg
*click*

    

     -- Allan


Edited by AllanDystrup, 09 December 2019 - 01:40 AM.

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#60 AllanDystrup

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Posted 11 December 2019 - 03:33 AM

.

The Moon, age ~6 days, S area.

    

    

     Continuing down S, the Nectaris basin is prominently centered, like a bull’s eye on the SE lunar limb, with the W and S sectors showing a well defined 4-ring structure, while the two outer rings (#3, #4) are more degraded by younger deposits towards the N and E; The Altai Scarp (ring #4) is obvious from Piccolomini in the S to Hypatia in the N, while the next inner ring (#3) is traceable from Santbech, down S of Fracastorius and up to the chain of large craters Catharina-Cyrillus-Theophilus towards the W. Ring #2 delineates the small circular Nectaris mare shore with the Pyrenees Mountains towards the E, and finally an inner wrinkle-ridge ring (#1) can be seen, most conspicuous towards the W and E.

     The reason that the multi-ring structure of Nectaris is weakest towards the NE is probably that the two old pre-Nectarian basins Tranquillitatis and Fecunditatis had already hammered this sector, thus thinning and weakening the crust, and so during the lava flooding in upper Imbrium, the lowest and weakest ring structure of Nectaris in this area was mostly submerged, apart from a rectangular patch of highland between the two pre-Nectarian mares (named “Colchis” by Hevelius in 1647).

    
     The Nectaris basin also shows a strong radially lineate sculpture from secondary impacts chains, notably the Rheita and Snellius Valleys towards the SE. (There are also some crater chains towards the N (Hypatia, Capella), but these were formed later, by the Imbrium impact).

     The large and young Eratosthenian crater Theophilus is spectacular in the lunar sunrise with its steep rim crest, terraced inner wall and flat floor with a tight group of three central peaks, -- that are not quite resolved at 86x tonight. I can however see how the impact melts have “splashed” up over the NE lower crater rim to form a frayed ejecta carpet on the mare surface of Sinus Asperitatis. The albedo of M. Nectaris show many interesting details, such as the small (L, 4.4km Ø) craterlet Beaumont L that has a halo of dug-up darker lava, and the crater Rosse (R, 12km Ø), which is crossed by a bright ejecta ray from the recent Copernican Tycho impact.

    

Moon 6DY S.jpg
*click*

     
     So many interesting structures to study in this area, but I have to end my observation now, as our youngest grandchild has arrived at our doorstep.

    

     -- Allan

 

PS: A view through my eyepiece of the central area of the 6-day crescent Moon: https://youtu.be/ajuXKSob8FU. -- Not the best seeing, but useable.


Edited by AllanDystrup, 11 December 2019 - 03:53 AM.

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#61 AllanDystrup

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Posted 19 December 2019 - 02:03 AM

.

     Still overcast, rainy and windy here in N. Europe, so I have been entertaining myself by piecing together this
    

Quick schematic overview
of the present-day moon near-side SURFACE geology.

         

    

     Starting from the south pole, we first encounter the ancient (4.4 Byr) pre-Nectarian highlands consisting of old cratered lunar crust, bounded on all sides by ejecta from surrounding impact basins (Orientale, Humorum, Nubium, Nectaris). The highland area itself show many impact craters, but no deep basins, lava fills or prominent traces of vulcanism.

         

     Moving counter clockwise up along the eastern side of the crescent moon, the surface is here dominated by Nectarian basin material (3.92 Byr) covering the earlier pre-Nectarian impact excavations, apart from the large Fecunditatis basin. Much of the surface material in this lunar region has been provided by ejecta from the Nectarian Crisium and Nectaris basins.

    

     Continuing past the North Pole, we arrive at the large north-central part of the near-side moon, which is covered by ejecta from the Imbrian basin that marks the start of the lower (early) Imbrian epoch (3.85 Byr).

 

     Finally, the south-east area is dominated by ejecta from the Orientale basin impact (3.8 Byr), which marks the start of the upper (late) Imbrian epoch.

     The large impact basins on the lunar near-side were all lava filled later in this upper Imbrian epoch, with a smaller lava flooding taking place in the east Procellarum-Imbrium basin early in the Eratosthenian epoch (3.2 Byr).

    

    

Lunar History-Landscapes.png

*click*

    
     This counter-clockwise sweep of the of the lunar surface is of course grossly simplified, but I like it as a step-wise way of presenting how the Moon’s geological history is expressed in the current main landscape areas. 

 

     Hoping for clear skies soon...

          -- Allan


Edited by AllanDystrup, 19 December 2019 - 02:05 AM.

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#62 AllanDystrup

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Posted 19 December 2019 - 02:57 AM

.

The Orientale Basin

    

    
     As it is, the weather cleared up partially this AM (10:30 local), offering a view of the 21-day waning gibbous moon, setting at 7° altitude towards the west. Certainly not optimal conditions for moon observation, but I rushed out my 4” refractor and had a quick study of the W half our satellite, with a focus on the upper Imbrian Orientale basin, which -- with a longitudinal libration of -1° -- was slightly tilted towards our line of sight.

    
     The basin itself was beyond the W rim, but I could see:
     • the Inner Rook Mountain chain (Ring #1) as a bright line along the horizon
     • the Lacus Veris mare strip stretched out between the Inner and Outer Rook Mtns
     • the Outer Rook Mtns (Ring #2), -- a line of massifs in front of the lake Veris
     • the S-shape of the Lacus Autumni mare strip just inside the Cordillera ring
     • the Cordillera Mtns (Ring #3), most visible east of Byrgius A
    

    
      I’m looking forward to study this the latest large lunar basin impact at a more favorable libration, illumination and magnification, -- but good to at least catch a view of our Moon again smile.gif

    

     Here’s a quick recording from my observation, -- pale because of the daylight and somewhat striated because of the phone camera, but never the less.

 

2019-12-19 Moon Thumb.jpg

A better view: Attached File  Moon 2019-12-18.pdf   439.2KB   25 downloads

    

     -- Allan


Edited by AllanDystrup, 19 December 2019 - 09:29 AM.

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#63 AllanDystrup

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Posted 20 December 2019 - 08:56 AM

.

    

     Moving further south along the W limb of the Moon, I can identify several interesting older formations below the otherwise primarily upper Imbrian Orientale ejecta carpet.

    
     First, there are a couple of old pre-Nectarian basins, most obvious of course the large basin that holds Mare Nubium, but also -- much more subtle -- the ancient Flamsteed-Billy and Insularum Basins, now mostly buried below Mare Procellarum.

     Furthermore, I can see the 2-ring Grimaldi basin towards the west and the 3-ring Schiller-Zucchius basin plus the 2-ring Bailly basin in the far south-west area.  

     The Grimaldi rings are best seen at a lower solar angle, but the S-Z and Bailly basins are fairly easily recognized, even here in broad daylight at a 59% waning Moon. The large (227km Ø) pre-Nectarian crater Schickard shows an interesting big bright wedge of Orientale basin ejecta, covering the central part of the otherwise dark lava filled floor.

    
     From the later Nectarian epoch, the Humorum basin is most prominent, with traces of a 3-ringed structure, and several large Nectarian craters can also be seen, like Gassendi at the N rim of Humorum and Schiller towards the SW edge.

    

2019-12-18 S Thumb.jpg
Full resolution: Attached File  Moon 2019-12-18 S.pdf   381.87KB   25 downloads

    

     -- Allan

 

 

 


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#64 AllanDystrup

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Posted 05 January 2020 - 07:49 AM

.    

The Moon, age ~9 days.

    

    

     It’s an early evening in the start of January (2020-01-04, 17:30), and I’m out, setting up in astronomical dusk, to study the 9 days waxing moon (64% illuminated) up at a good 36° altitude above the SSE horizon, in southern Pisces. The temperature is a cool 3°C with a relatively low humidity of 61%, and the dew point is way down at -4°C. The LP is a Bortle 5/6 bright/suburban (aka. NELM 5.6 ~ SQM 19.0), and the transparency is medium at 3-4/7 with a faint moon halo from high Cirrus, whereas a train of low drifting Cumulus Humilis have now been swept down south and are thus well out of the way. The seeing is a moderate 5-6/10, with a medium wind from the NW interrupted by intermittent stronger gusts that can “shake, rattle and rock-n-roll” my small 100/640mm refractor, although it is solidly mounted on my sturdy Zeiss Ib tripod.

         

      I’ve now set up my telescope, initially for a full disc view of the Moon at 98x magnification in a 1° FOV (4” f/6.4 refractor w. 2x barlow + 13mm 100°AFOV EP). The max libration is in deep lunar night up NW (+7° lat., +4° long.), but this evening I’ll be focusing on the terminator area of the 9-day half Moon, which crosses from the central Imbrium basin down south through the central Nubium basin, and thus offers a favorable view of:

    

MOON 9Day 2020-01-04.jpg
*click*

    
On the N hemisphere:

  • The N- Polar highland region, from the crater pair Goldschmidt (pre-Nectarian)-Anaxagoras (Copernican) and up N past the craters Scoresby and Byrd-Peary to the pole.
     
  • The E multi-ring Imbrium sculpture (3.8 Byr) including:
    • The inner concentric mare ridges, which borders to the E on the partly submerged peaks of the inner ring (#1): from the Straight Range, past Mts. Tenerife, Pico, Spitzbergen and Archimedes.
    • The topographic basin rim, which is the probable excavation boundary (#2), from the Mts. Alpes past the Caucasus to the Apennines and Carpathians and possibly past the mostly buried Mts. Harbinger (now in deep night W of the terminator).
  • The regions bordering on the Imbrium basin to the N and S are both located inside the excavation of the older (pre-Nectarian) and larger Procellarum basin, and as such they were lava covered in the upper Imbrian epoch:
    • The N trough outside the Mts. Alpes is now seen as the lava-filled Mare Frigoris moat, while
    • The S trough outside the Mts. Apennines is filled with the Sinus Vaporum-Aestuum lava plains that harbor the volcanic Bode and Aestuum pyroclastic areas.

 On the S hemisphere:

  • The old Pre-Nectarian Nubium basin is seen flanked on the E shore by the “Great Peninsula” (as Dinsmore Alter named it), with the prominent large complex craters Ptolemaeus - Albateginus, Alphonsus, Arzachel and Purbach.
     
  • The S-Polar highland features a multitude of craters, including the prominent “diamond” pattern from Tycho past Longomontanus – Maginus to Clavius towards the S.

     
     It's now well past 18:00h and I'm thus into proper astronomical night; As I start to click up the magnification, more details are revealed in these lunar areas.

 

     -- Allan


Edited by AllanDystrup, 05 January 2020 - 10:05 AM.

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#65 AllanDystrup

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Posted 06 January 2020 - 06:54 AM

.

The Moon, age ~9 days, N area.

    

    

     I now crank up the magnification to 122x in a 0.8° TFOV (FFC@4x barlow+ 21mm EP); This gives me a good view of the lunar terminator, first through the N and thereafter the S hemisphere. In the images below, I’ve included the appropriate segments of the Wilhelms-McCauley lunar geology map from 1971 as an illustration of the  origin of the main terrain features; Note that this source presents a more detailed interpretation of the Imbrium basin morphology with 3 rings: the inner concentric wrinkle-ridge ring #1, an intermediate ring #2 (1.200km Ø) through the Mts. Alpes and Archimedes, plus an outer basin rim ring #3 (1.500km Ø) from the Mts. Carpathian up through the Apennines and continuing along the Caucasus to enclose Mare Frigoris towards the N.

    

     There is thus some ambiguity as to the true excavation boundary and topographic rim of the Imbrium protoplanet impact basin, especially in the NE and SW sectors. Apollo rock analysis has showed that the Apennine Bench (S of Archimedes) is -- at least partly -- of igneous origin (KREEP), erupted ~3.84 Byr ago on the basin floor shortly after the Imbrium impact, and thus the Mts. Archimedes may not be uplifted crust in a #2 basin ring, but rather of endogenic origin combined with slumps from the Apennine scarp, which would favor the 2-ring interpretation.

    

     The area immediately SE of the Carpathian-Apennine Imbrium rim has been covered by a thick, hilly carpet of light-hued basin ejecta with radial SE tapering lineate structures of rocky hummocks and wedges of melt deposits, in which the lower regions have later (in Upper Imbrian) been partly flooded by small lava lakes (Sinus Vaporum, Aestuum etc.). This area has experienced tremendous stress in connection with the crust uplifting, and that shows up in several tectonic straight rilles (grabens) as well as volcanic sinuous rilles (collapsed lava channels and uplift fractures); This is the region that Charles Wood called “Rilleland”. In particular, Sinus Aestuum shows prominent areas of fine volcanic ash and glass deposits from explosive fire fountain volcanism (dark mantle deposits: DMD), notably towards the E shore (Bode pyroclastics) and the S shore (Aestuum pyroclastics). The DMD layer probably continues from the Bode and Aestuum areas, west to S of Copernicus, but here it has been partly covered by upper Imbrian lava flooding with Eratosthenian and Copernican ejecta on top.

    

     9Day Moon N 2020-01-04.jpg
*click*

    

     -- Allan


Edited by AllanDystrup, 06 January 2020 - 06:55 AM.

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#66 AllanDystrup

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Posted 06 January 2020 - 10:26 AM

.

Imbrium, closer up.

    

    
          Here’s a couple of closer-up views (~200x @ 0.5°) from my observation of the 9-Day moon: Left: the N part of Imbrium with the Alpes Mountains and the long Alpine Valley graben, and Right: the S Imbrium region around Sinus Aestuum with DMD pyroclastics and the hummocky Copernicus ejecta carpet draped over Mare Insularum.

    

     There’s a long crater chain (catena) winding south between Copernicus and Eratosthenes, down to the almost submerged lower Imbrian crater: Stadius. I assume this is secondary craters from the Copernicus impact, or??

    

9Day Moon - N Imbrium.jpg

*click*

 

     -- Allan


Edited by AllanDystrup, 06 January 2020 - 10:31 AM.

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#67 AllanDystrup

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Posted 07 January 2020 - 03:39 AM

.

The Moon, age ~9 days, S area.

    

    

     Moving on to the S hemisphere of the 9-Day half-moon, we first encounter the light-colored highland crust of the “Great Peninsula” (D. Alter); Towards the W, the Peninsula is mostly covered by impact ejecta from the Imbrium basin (the planar melt-rich Cayley stratigraphy), while towards the E, the Imbrium ejecta is has been mixed up with deposits from the underlying Nectaris basin (the furrowed Descartes stratigraphy). The Imbrian origin of much of the surface material on the Peninsula is evident from the system of groves and chains of secondary impact craters radiating from the Imbrium Basin (the “Imbrium Sculpture”).

    

     The W part of the Peninsula is dominated by large, complex craters: first the old Pre-Nectarian Hipparchus, Ptolemaeus, Purbach and Ancient Thebit (with the Straight Wall), the last one partly covered by lava on the border to Mare Nubium. Then the younger Nectarian “triple-A” craters: Albateginus, Alphonsus (with several DMD patches) and Alpetragius (with the Egg-in-Nest rounded peak). Finally, we come to the youngest (lower Imbrian) crater Arzachel, with its spectacular 1km high and steeply terraced walls.

    

    

    Panning further S, we encounter the ancient pre-Nectarian “Southern Cratered Highlands”, with a multitude of craters on top of other craters. The most obvious landmark in the region below Nubium is the “diamond” arrangement of large complex craters marked by Tyco to the N and Clavius to the S, and with Longomontanus and Maginus to the W and E respectively.

    

9Day Moon 2020-01-04 S.jpg

*click*

    

     -- Allan


Edited by AllanDystrup, 07 January 2020 - 03:44 AM.

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#68 AllanDystrup

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Posted 08 January 2020 - 03:41 AM

.

The Peninsula & S Highlands, closer up.

    

    
          Here’s a couple of closer-up views (~200x @ 0.5°) from my observation of the 9-Day moon, south hemisphere.

    
     To the left: the W part of the ”Great Peninsula”, first focusing on Alphonsus which shows a N-S diagonal ridge of Imbrium ejecta, a couple of later (Eratosthenian?) W and E pyroclastic dark areas (DMD) plus a dark haloed crater ‘R’ towards the south. Furthermore, in the pre-Nectarian lava-drowned crater Ancient Thebit is seen the 400m high scarp “the Straight Wall” which is a fault created by Mare Nubium subsidence after the lava flooding in upper Imbrian. I can also *just* glimpse Rima Birt, a collapsed lava channel running parallel to the Wall a little to the W.

    
     To the right: in the rugged S highlands Copernican Tycho and Nectarian Clavius stand out, the latter with an arc of craters, from large D (28Km Ø) to small J (12 KM Ø), plus minute CB (9Km Ø). A basin size impact will first throw out large, early-arriving clots of ejecta in relatively low ballistic trajectories, which will create secondary craters up to a great distance (>1000Km) from the basin. This shows up as elliptical pits, chains and furrows/gouges radial to the basin center (the basin sculpture). This first wave is shortly followed by a slower-moving ground surge of a finer, coarsely textured blend of impact melt and crust debris (the ejecta blanket), which will gradually thin out to more smooth plain deposits that will partly overrun/overlay the sculpture closest to the basin rim. Scattered Imbrium secondary craters can be found today >3000Km from the basin center, and so the crater chain in Clavius could in theory be an Imbrium basin catena, -- but it is not radial to this basin. It is in fact more radial to the Orientale basin, and I believe I’ve read somewhere that it may probably be an Orientale catena (but I can’t find the reference now... – maybe someone here knows more about it?).

    

9-Day Moon 2020-01-04.jpg
*click*

    

     -- Allan


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#69 j.gardavsky

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Posted 08 January 2020 - 05:05 AM

Hello Allan,

 

a very interesting note on the catena of craters in Clavius.

Thank you,

JG


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#70 AllanDystrup

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Posted 11 January 2020 - 08:42 AM

.

The Moon, age ~13 days.

    

    

     It’s an early evening in the start of January (2020-01-08, 19:00 CEST UT+1). My weather apps say: “overcast”, and yes, there is a sheet of low Nimbostratus pannus coming in on a NW wind, but it has not quite closed the sky yet, so I rush out my small refractor to (hopefully) get some observations of the 13-day (95%) waxing gibbous Moon high up at 38°, speared on the southern horn of Taurus towards the SE.

    
     The temperature is mild for the season (5°C) with a relatively high humidity of 81%, and with the dew point close by (at 2°C) the Moon is now centered in a halo of high ice crystals. Overall the transparency is a horrible 2-3/7 but the seeing is an OK 6-7/10 with minor shimmering of the moon image. In such circumstances I can always rely on my short f/6.4 four-inch oiled refractor with a well-insulated lens cell, as it is always ready to go within the 10 minutes it takes me to setup the gear, and from here it just gently slides down the temp. diff. slope (Δ 15°C tonight) to ambient, without degrading the excellent view quality smile.gif.

    
     The most striking feature on the W side of the almost full Moon is the obvious large arc described by the border between Oceanus Procellarum and the highlands towards the W lunar limb; The lunar scientist Ewen Whitaker was the first to suggest that this border was probably the excavation rim of a large pre-Nectarian basin (later named “Gargantuum”), and by continuing to trace mare borders (such as the arcuate trough of Mare Frigoris) and some highland ridges (such as the terrain W of Taurus Mountains), he suggested that the impact had created 3 rings (marked on my image below); However, as the estimated age of Gargantuum is ~4.3 Byr, the Moon was still hot and plastic at the time of impact, so as expected, the rings probably in a short time subsided and only the later Imbrian lava fill of the basin plus a  few arcuate highland ridges now remain for us to “connect the dots”.

          
 Moon 13DY all 2020-01-08.jpg

*click*

To-be-continued...

     -- Allan


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#71 AllanDystrup

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Posted 11 January 2020 - 08:46 AM

.

The Moon, age ~13 days (NW areas)

    

    

     All along the NW rim of the Gargantuan Basin are traces of volcanic activity: from the Rümker Hill coalescing domes with a large caldera towards the E, past the uplifted block of the Aristarchus Plateau with lava covering from Schröter’s Valley and DMD mantling from the Cobra Head vent, to the ancient magma hot-spot Marius Hills that now features several hundred small volcanic cones. This extraordinary concentration of volcanic complexes was probably initiated by the Imbrium impact into the already thin crust excavated by the pre-Nectarian Gargantuum asteroid.

    

Moon 13DY NW 2020-01-08.jpg
*click*

     -- Allan


Edited by AllanDystrup, 11 January 2020 - 08:52 AM.

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#72 AllanDystrup

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Posted 13 January 2020 - 04:14 AM

.

Gargantuum / Procellarum.

    

    

     For completeness, here’s an outline of the Gargantuum basin with the main geological landforms (mare plains and largest craters) that has later filled in the excavation (Wilhelms Geological Map, as pr. 2013 renovation. LROC Quickmap) :

 

Procellarum Geo Map.jpg
*click*

    

     -- Allan


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#73 Eagle Butte Observatory

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Posted 13 January 2020 - 09:52 PM

I used to think of the moon as merely annoying light pollution!  What’s worse is the clearest nights tend to have the moon bright in the night sky.  One night out in my observatory while I was complaining about the moon one of my observing buddies suggested we take advantage of the clear steady air and look at the moon...what a treat!! The moon is amazing and if the seeing is good the moon is as good as it gets.  


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#74 AllanDystrup

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Posted 14 January 2020 - 06:54 AM

.
Rod,
     I find the Moon especially fascinating now we (humanity) are going back there (and further on to Mars in the coming years). I was very excited back in the first decade of 2000, when NASA finally started the Constellation project with design of the Orion spacecraft for returning to the Moon. Unfortunately, this visionary project was moth balled and NASA resources were instead cut back and directed towards LEO ISS + shuttle space research; Fine, but not really pushing the limits of what the US had accomplished with the Apollo project.

     So now we’re essentially back at where we left 20 years ago (and 50 years after Apollo), dusting off the daring visions, now with the Artemis SLS and Orion plans for new lunar surface explorations through landers, rovers, EVAs, outposts... I want to familiarize myself with the Lunar environment -- landscapes, physiography, geology – before we take off once again to the Moon.

         

    

The Death Star

    
    
     It’s an early morning in mid-January (2020-01-13, 07:30 AM, CEST UT+1), and my wife has alerted me that the Moon is shining bright outside in our backyard! After another week of overcast and rainy weather, that is good news, so even though we’re right now transiting from nautical to civil twilight and there are strands of high cirrus drifting by, I seize the opportunity to set up my 4” refractor for a quick study of the 13-day (91% waning Moon), which is now dangling like a ripe fruit up at 12° towards the W, ready to be harvested by the sickle of Leo right above.

    
     The moon in this phase has an uncanny resemblance to a not quite completed Star Wars Death Star, with its super-laser presumably already able to shoot out from the Crisium basin, ready to pulverize any rebellion planet... Undeterred I direct my own small Z-BOLT laser at the Moon, and immediately lock onto it in the FOV of my 4” refractor! Even at low magnification (30x), the most striking feature is the western inner blocky ring (#2) of the Nectarian Crisium basin, composed of up to 5km high, elongated mountain massifs, that cast long serrated shadows into the basin, which is now covered by mare lavas from the Upper Imbrian lava flooding (Im2). At higher magnification (80x), I can see the mare ridge (Dorsum Oppel) at the inner shelf/bench after the central lava subsidence, and several Eratosthenian mare craters (Swift, Pierce, Picard) can be studied in nice “profile” on the mare plain.


     S of Crisium in the now mare-filled, old pre-Nectarian Fecunditatis basin, the Copernican Messier crater pair catches the eye, -- the result of a low grazing impact coming in from the E (~3° altitude), ricocheting downrange and ejecting a long bright ray across Mare Fecunditatis. Prominent also in Fecunditatis at this low illumination are the two mare ridges: Geikie and Mawson.
    


18Day Moon disc.jpg
*click*

    

     -- Allan

Edited by AllanDystrup, 14 January 2020 - 07:10 AM.


#75 AllanDystrup

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Posted 14 January 2020 - 07:02 AM

18Day Moon CloseUp.jpg


-- Allan
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