DOCSLIB.ORG

Distribution, Morphology, and Origin of Ridges and Arches in Mare Serenitatis

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Distribution, Morphology, and Origin of Ridges and Arches in Mare Serenitatis Distribution, Morphology, and Origin of Ridges and Arches in Mare Serenitatis T. A. MAXWELL Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112 FAROUK EL-BAZ National Air and Space Museum, Smithsonian Institution, Washington, D.C. 20560 S. H. WARD Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah 84112 ABSTRACT The Apollo Lunar Sounder Experiment (ALSE) flown on Apollo 17 has produced profiles that are useful in the study of mare ridge Lunar mare ridges and arches in Mare Serenitatis were mapped systems (Phillips and others, 1973). A continuous radar profile to understand better their mode of formation. Mapping of these from the VHF mode (150 MHz) is used as a detailed topographic features indicates that several pre-mare impacts in the Serenitatis profile across ridges in southern Serenitatis, from which slopes and area may be responsible for the localization of the circular ridge elevations of the ridges and the amount of east-west crustal short- systems and that the subsurface, pre-mare topography is more ening have been measured. complex than previously recognized. Locations of the Serenitatis ridge systems were mapped, using as Apollo Lunar Sounder cross sections of ridge systems in southern a base the 1:2,750,000 scale Lunar Orbital Science Flight Chart Serenitatis indicate 50 to 100 m of local relief on these features. produced by the Defense Mapping Agency Aerospace Center for Ridges in the southwestern part of the basin mark the boundary of the National Aeronautics and Space Administration. In mapping a bench 200 m above the local mare level. As reflected in their the ridge systems, we used Apollo metric and pan photographs and orientation, arches and ridges are possibly controlled both by rings additional Earth-based photographs from the Consolidated Lunar of pre-mare basins resulting from impacts and by a more wide- Atlas (Kuiper and others, 1967). The purpose of this paper is to (1) spread global stress system. Small-scale features of ridges, such as summarize our observations on the distribution of ridges and medial lineations and lobate margins, do not conclusively define arches in Mare Serenitatis, (2) discuss these features in relation to the origin of the ridges. However, estimates of crustal shortening the Serenitatis basin and possibly more widespread stress systems, from Lunar Sounder data and the coincidence of the major ridge and (3) describe the morphology of ridges and arches in Mare system with the Serenitatis mascon suggest that ridges and arches Serenitatis in order to understand better their origin. were formed by gravitational readjustments of the mare fill along four probable impact structures and along a north-trending frac- DISTRIBUTION ture pattern. Key words: lunar morphology, lunar tectonics, lunar ridges and arches. Ridges and arches in Mare Serenitatis exhibit five dominant trends, four of which are related to circular pre-mare impacts. A INTRODUCTION general northward trend is also evident. The dominant ridge-system orientation (400 km in diameter; A Although lunar ridges occur in the highlands, they are usually in Fig. 1) is coincident with the inner ring of the Serenitatis basin as best exposed in the lunar maria, where they either parallel the mapped by Wilhelms and McCauley (1971), but as has been noted trends of the lunar grid system (Strom, 1964) or form trends con- for ridge systems in other maria, the system is not continuous; seg- centric with the major basins. These topographic forms have been ments of ridges and more continuous arches vary locally in orienta- referred to as "mare ridges" or "wrinkle ridges." tion. In western Mare Serenitatis, the ridges mark the boundary of Four basic hypotheses have been used to explain the origin of a topographic bench, which is raised relative to the center of the mare ridges and arches: a thin lava veneer on high ridges of pre- basin. Phillips and others (1972) showed that these benches coin- mare ground (Baldwin, 1963); tectonic deformation resulting from cide with the edges of a near-surface disk model for mascons in the shrinkage and isostatic subsidence of mare lava flows (Bryan, both Serenitatis and Crisium. Both ridges and arches are associated 1973); intrusive volcanism in the form of laccoliths or sills that lo- with the bench in western Serenitatis, and their occurrence is quite cally dome the surface (Whitaker, 1966; Strom, 1972); and extru- similar to the coincidence of a ridge system and the bench in west- sive volcanism of repeated flows to form both arches and ridges ern Crisium. (Young and others, 1973; Hodges, 1973). Combinations of the Three other circular ridge systems are also evident in Serenitatis. above hypotheses were favored by Tjia (1970), Hartmann and East of Bessel, a small ridge system, 140 km in diameter (B in Fig. Wood (1971), and Colton and others (1972). Recently, a tectonic 1), is coincident in the southeast with ridges that mark the inner mode of formation was advocated for ridge systems in Imbrium ring of the Serenitatis basin. The western limb of the "B ridge sys- (Schaber, 1973) and Serenitatis (Howard and Muehlberger, 1973; tem" extends in a north-south arc through the south-central part of Muehlberger, 1974). the basin. The mare area immediately to the north is smooth, and Adhering to the terminology proposed by Strom (1972), there is no evidence for the continuation of this ring, even when wrinkle-ridge systems in Serenitatis are divided here into mare photographed at lowest sun elevations. Evidence for the B ridge ridges and arches: arches have smooth slopes nearly indistinguish- system consists solely of the northward arc of ridges through Bes- able from the surrounding mare except under illumination at low sel. This trend may be the result of a north-south submare struc- sun elevation; ridges are smaller and have sharper edges. The term ture, but a circular structure as outlined in Figure 1 is preferred. At "ridge system" is reserved for both ridges and arches following the the northern boundary of Serenitatis, two circular ridge systems are same general trend. more clearly distinguished by discontinuous mare ridges and Geological Society of America Bulletin, v. 86, p. 1273-1278, 6 figs., September 1975, Doc. no. 50910. 1273 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/86/9/1273/3418522/i0016-7606-86-9-1273.pdf by guest on 29 September 2021 1274 MAXWELL AND OTHERS MORPHOLOGY The apparent difference between mare ridges and arches is most evident at low sun angles in Earth-based and lunar orbital photo- graphs; orbital radar (ALSE) has justified this distinction. Although detailed observations of the ridges and arches do not conclusively define the origin of these features, it is apparent that the ridges have been subjected to several periods of deformation. Lobate fronts (A in Fig. 3) that subdue neighboring topography at the edges of ridges have been used to indicate flows and, there- fore, an extrusive volcanic origin for the ridges (Strom, 1972). However, the possibility remains that these features may result from debris slides of regolith on the flanks of the high standing ridges (Bryan, 1973; R. S. Saunders, 1974, oral commun.). Many of these lobate fronts occur on low-angle slopes and are conspicu- ous in the interior of neighboring craters, thus indicating that slumping may be a valid mechanism of formation. Crests of mare ridges are in places characterized by parallel line- aments (B in Fig. 3) that trend in the same direction as the ridges (medial lineations). These lineations are found only on the crests of ridges and contribute to the youthful appearance; they do not ap- pear on mare arches. Slumping on the sides of ridges may be par- tially responsible for local tension that could produce the linea- tions. However, their dominant orientation, which persists despite the proximity of ridge scarps, suggests a deeper structural control. Similar lineations or parallel fractures appear on the relatively level mare in eastern Mare Serenitatis (Apollo 15 pan frame 9301), I6*N where they may be related to the same stress that produced the 26»E 30*E larger rilles in the dark mare surrounding Serenitatis (Muehlberger, C-3E? MARE ARCH MARE-HIGHLAND BOUNDARY 1974). Two areas in southern Serenitatis show a variety of relationships MARE RIDGE SCARP (BALL ON LOWER SIDE) between mare ridges and arches. Both the inner-ring ridge system Figure 1. Map of Mare Serenitatis showing distribution of mare ridges and the B ridge system roughly coincide in southeastern Serenitatis and arches. Dotted circles mark trends of ridge systems: A, inner ring; B, C, (Fig. 4). Although both ridges and arches follow the same general and D, three smaller structures. trends, there is no consistent feature that permits the ridges and arches to be assigned to either the inner-ring or the B ridge system. arches. The northeastern system, the "C ridge system" (330 km in Mare ridges in this region may form at the crest of an arch or on the diameter), continues from the mare into Serenitatis rim materials, boundary of an arch, or they may continue in smoother mare mate- but it is marked there by a scarp instead of ridges as in the mare rial that has no apparent relationship to arches (Fig. 4). (Fig. 1). Southwest of Posidonius, the continuation is marked by a Mare ridges in this area may, however, be distinguished as to age subdued arcuate rille, most likely a graben (R in Fig. 1). This sys- on the basis of their sharpness. East of the main ridge system in tem is unique because of changes in its character — grading from Figure 4, a more subdued ridge is present in relatively smooth, ridges in the mare to a probable fault in the highlands.
Load more

Recommended publications
  • TRANSIENT LUNAR PHENOMENA: REGULARITY and REALITY Arlin P
    The Astrophysical Journal, 697:1–15, 2009 May 20 doi:10.1088/0004-637X/697/1/1 C 2009. The American Astronomical Society. All rights reserved. Printed in the U.S.A. TRANSIENT LUNAR PHENOMENA: REGULARITY AND REALITY Arlin P. S. Crotts Department of Astronomy, Columbia University, Columbia Astrophysics Laboratory, 550 West 120th Street, New York, NY 10027, USA Received 2007 June 27; accepted 2009 February 20; published 2009 April 30 ABSTRACT Transient lunar phenomena (TLPs) have been reported for centuries, but their nature is largely unsettled, and even their existence as a coherent phenomenon is controversial. Nonetheless, TLP data show regularities in the observations; a key question is whether this structure is imposed by processes tied to the lunar surface, or by terrestrial atmospheric or human observer effects. I interrogate an extensive catalog of TLPs to gauge how human factors determine the distribution of TLP reports. The sample is grouped according to variables which should produce differing results if determining factors involve humans, and not reflecting phenomena tied to the lunar surface. Features dependent on human factors can then be excluded. Regardless of how the sample is split, the results are similar: ∼50% of reports originate from near Aristarchus, ∼16% from Plato, ∼6% from recent, major impacts (Copernicus, Kepler, Tycho, and Aristarchus), plus several at Grimaldi. Mare Crisium produces a robust signal in some cases (however, Crisium is too large for a “feature” as defined). TLP count consistency for these features indicates that ∼80% of these may be real. Some commonly reported sites disappear from the robust averages, including Alphonsus, Ross D, and Gassendi.
    [Show full text]
  • Radar Remote Sensing of Pyroclastic Deposits in the Southern Mare Serenitatis and Mare Vaporum Regions of the Moon Lynn M
    JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 114, E11004, doi:10.1029/2009JE003406, 2009 Click Here for Full Article Radar remote sensing of pyroclastic deposits in the southern Mare Serenitatis and Mare Vaporum regions of the Moon Lynn M. Carter,1 Bruce A. Campbell,1 B. Ray Hawke,2 Donald B. Campbell,3 and Michael C. Nolan4 Received 21 April 2009; revised 12 July 2009; accepted 3 August 2009; published 5 November 2009. [1] We use polarimetric radar observations to study the distribution, depth, and embedded rock abundance of nearside lunar pyroclastic deposits. Radar images were obtained for Mare Vaporum and the southern half of Mare Serenitatis; the imaged areas contain the large Rima Bode, Mare Vaporum, Sulpicius Gallus, and Taurus-Littrow pyroclastic deposits. Potential pyroclastic deposits at Rima Hyginus crater, the Tacquet Formation, and a dome in Mare Vaporum are also included. Data were acquired at S band (12.6 cm wavelength) using Arecibo Observatory and the Green Bank Telescope in a bistatic configuration. The S band images have resolutions between 20 and 100 m/pixel. The pyroclastic deposits appear dark to the radar and have low circular polarization ratios at S band wavelengths because they are smooth, easily penetrable by radar waves, and generally contain few embedded blocks. Changes in circular polarization ratio (CPR) across some of the pyroclastic deposits show areas with increased rock abundance as well as deposits that are shallower. Radar backscatter and CPR maps are used to identify fine-grained mantling deposits in cases where optical and near-infrared data are ambiguous about the presence of pyroclastics.
    [Show full text]
  • Relative Ages
    CONTENTS Page Introduction ...................................................... 123 Stratigraphic nomenclature ........................................ 123 Superpositions ................................................... 125 Mare-crater relations .......................................... 125 Crater-crater relations .......................................... 127 Basin-crater relations .......................................... 127 Mapping conventions .......................................... 127 Crater dating .................................................... 129 General principles ............................................. 129 Size-frequency relations ........................................ 129 Morphology of large craters .................................... 129 Morphology of small craters, by Newell J. Fask .................. 131 D, method .................................................... 133 Summary ........................................................ 133 table 7.1). The first three of these sequences, which are older than INTRODUCTION the visible mare materials, are also dominated internally by the The goals of both terrestrial and lunar stratigraphy are to inte- deposits of basins. The fourth (youngest) sequence consists of mare grate geologic units into a stratigraphic column applicable over the and crater materials. This chapter explains the general methods of whole planet and to calibrate this column with absolute ages. The stratigraphic analysis that are employed in the next six chapters first step in reconstructing
    [Show full text]
  • Geological Evolution of the Largest Shield Volcano Bearing Mare of The
    52nd Lunar and Planetary Science Conference 2021 (LPI Contrib. No. 2548) 1827.pdf GEOLOGICAL EVOLUTION OF THE LARGEST SHIELD VOLCANO BEARING MARE OF THE MOON, MARE TRANQUILLITATIS: BASED ON DETAILED MORPHOLOGICAL, MINERALOGICAL, TOPOGRAPHIC STUDIES USING MULTIPLE DATA SETS. Henal Bhatt1, P. Chauhan2, Paras Solanki1, 1M. G. Science Institute, Ahmedabad 380009, India, 2Indian Institute of Remote Sensing, (ISRO), Dehradun, Uttarakhand, India. ([email protected] ) Introduction: In this work, we have analysed the Results and Discussions: Mare Tranquillitatis is irregular shaped Mare Tranquillitatis based on its delineated in to 22 spectral units based on IBD parameter morphology, mineralogy and topography to understand its analysis (Fig. 1). The band parameters analysis was geological evolution in the Lunar formation history. This conducted as per [8], [9], [10] suggest the abundance of area is very unique as it resides the largest shield volcano mafic silicate mixture, particular, mixture of olivine and of the Moon, compared to all the other circular mare basins medium to high calcium pyroxene bearing basaltic material at the near side of the Moon. It is located towards eastern in the area (Fig. 1). Details of this analysis is reported in the near side at 7°N, 30°E and is a Pre-Nectarian age basin [1]. [11]. Graphical trends suggests that basalts of eastern shield It is well known for Apollo 11 landing site and it shows mare would have been comparatively more pyroxene characteristic two basin ring structure [2], with diameter of bearing compared to the basalts from western deepest part, 800 km from east to west. which would have been more olivine bearing compared to the eastern shield mare basalt (Fig.
    [Show full text]
  • Moon Viewing Guide
    MMoooonn MMaapp What lunar features can you find? Use this Moon Map & Viewing Guide to explore different areas of the Moon - no binoculars needed! MMoooonn VViieewwiinngg GGuuiiddee A quick look at the Moon in the night sky – even without binoculars - shows light areas and dark areas that reveal lunar history. Can you find these features? Use the Moon Map (above) to help. Sea of Tranquility (Mare Tanquilitatus) – Formed when a giant t! nd I asteroid hit the Moon almost 4 billion years ago, this 500-mile wide Fou dark, smooth, circular basin is the site of the Apollo 11 landing in 1969. Sea of Rains (Mare Imbrium) – Imbrium Basin is the largest t! nd I basin on the Moon that was formed by a giant asteroid almost 4 Fou billion years ago. Sea of Serenity (Mare Serenitatis) – Apollo 17 astronauts t! sampled some of the oldest rocks on the Moon from edges of nd I Fou the Sea of Serenity. These ancient rocks formed in the Moon’s magma ocean. Lunar Highlands – The lighter areas on the Moon are the lunar t! highlands. These are the oldest regions on the Moon; they formed nd I Fou from the magma ocean. Because they are so old, they have been hit by impact craters many times, making the highlands very rough. Want an extra challenge? If you have a telescope or pair of binoculars, try finding these features: Appenine Mountains (Montes Apenninus) – Did you know there are mountain ranges on the Moon? The rims of the craters and t! nd I basins rise high above the Moon’s surface.
    [Show full text]
  • Glossary of Lunar Terminology
    Glossary of Lunar Terminology albedo A measure of the reflectivity of the Moon's gabbro A coarse crystalline rock, often found in the visible surface. The Moon's albedo averages 0.07, which lunar highlands, containing plagioclase and pyroxene. means that its surface reflects, on average, 7% of the Anorthositic gabbros contain 65-78% calcium feldspar. light falling on it. gardening The process by which the Moon's surface is anorthosite A coarse-grained rock, largely composed of mixed with deeper layers, mainly as a result of meteor­ calcium feldspar, common on the Moon. itic bombardment. basalt A type of fine-grained volcanic rock containing ghost crater (ruined crater) The faint outline that remains the minerals pyroxene and plagioclase (calcium of a lunar crater that has been largely erased by some feldspar). Mare basalts are rich in iron and titanium, later action, usually lava flooding. while highland basalts are high in aluminum. glacis A gently sloping bank; an old term for the outer breccia A rock composed of a matrix oflarger, angular slope of a crater's walls. stony fragments and a finer, binding component. graben A sunken area between faults. caldera A type of volcanic crater formed primarily by a highlands The Moon's lighter-colored regions, which sinking of its floor rather than by the ejection of lava. are higher than their surroundings and thus not central peak A mountainous landform at or near the covered by dark lavas. Most highland features are the center of certain lunar craters, possibly formed by an rims or central peaks of impact sites.
    [Show full text]
  • Lunar Sourcebook : a User's Guide to the Moon
    4 LUNAR SURFACE PROCESSES Friedrich Hörz, Richard Grieve, Grant Heiken, Paul Spudis, and Alan Binder The Moon’s surface is not affected by atmosphere, encounters with each other and with larger planets water, or life, the three major agents for altering throughout the lifetime of the solar system. These terrestrial surfaces. In addition, the lunar surface has orbital alterations are generally minor, but they not been shaped by recent geological activity, because ensure that, over geological periods, collisions with the lunar crust and mantle have been relatively cold other bodies will occur. and rigid throughout most of geological time. When such a collision happens, two outcomes are Convective internal mass transport, which dominates possible. If “target” and “projectile” are of comparable the dynamic Earth, is therefore largely absent on the size, collisional fragmentation and annihilation Moon, and so are the geological effects of such occurs, producing a large number of much smaller internal motions—volcanism, uplift, faulting, and fragments. If the target object is very large compared subduction—that both create and destroy surfaces on to the projectile, it behaves as an “infinite halfspace,” Earth. The great contrast between the ancient, stable and the result is an impact crater in the target body. Moon and the active, dynamic Earth is most clearly For collisions in the asteroid belt, many of the shown by the ages of their surfaces. Nearly 80% of the resulting collisional fragments or crater ejecta escape entire solid surface of Earth is <200 m.y. old. In the gravitational field of the impacted object; many of contrast, >99% of the lunar surface formed more than these fragments are then further perturbed into 3 b.y.
    [Show full text]
  • Tectonic Evolution of Northwestern Imbrium of the Moon That Lasted In
    Daket et al. Earth, Planets and Space (2016) 68:157 DOI 10.1186/s40623-016-0531-0 FULL PAPER Open Access Tectonic evolution of northwestern Imbrium of the Moon that lasted in the Copernican Period Yuko Daket1* , Atsushi Yamaji1, Katsushi Sato1, Junichi Haruyama2, Tomokatsu Morota3, Makiko Ohtake2 and Tsuneo Matsunaga4 Abstract The formation ages of tectonic structures and their spatial distributions were studied in the northwestern Imbrium and Sinus Iridum regions using images obtained by Terrain Camera and Multiband Imager on board the SELENE spacecraft and the images obtained by Narrow Angle Camera on board LRO. The formation ages of mare ridges are constrained by the depositional ages of mare basalts, which are either deformed or dammed by the ridges. For this purpose, we defined stratigraphic units and determined their depositional ages by crater counting. The degradation levels of craters dislocated by tectonic structures were also used to determine the youngest limits of the ages of the tectonic activities. As a result, it was found that the contractions to form mare ridges lasted long after the deposition of the majority of the mare basalts. There are mare ridges that were tectonically active even in the Copernican Period. Those young structures are inconsistent with the mascon tectonics hypothesis, which attributes tectonic deforma- tions to the subsidence of voluminous basaltic fills. The global cooling or the cooling of the Procellarum KREEP Ter- rane region seems to be responsible for them. In addition, we found a graben that was active after the Eratosthenian Period. It suggests that the global or regional cooling has a stress level low enough to allow the local extensional tectonics.
    [Show full text]
  • Beresheet Lunar Landing Site Revealed 20 March 2019
    Beresheet lunar landing site revealed 20 March 2019 landing area that could jeopardize the touchdown. In addition, the scientists searched for a location on the Moon where the crust is magnetic, so as to allow the magnetometer on board the spacecraft to carry out its investigation. The landing site was selected together with Prof. Jim Head of Brown University, a member of the SpaceIL team who worked with the NASA Apollo program on landing site selection, among other things. "On the basis of our experience with Apollo, the Serenitatis sites favor both landing safety and scientific reward," he said. The topography of the 140 km (87 mi) diameter area The chosen site is located in the northeastern part containing the potential lunar landing sites in Mare of Mare Serenitatis, a few hundreds of miles east of Serenitatis (arrow). Darker colors indicate lower elevation. Credit: Weizmann Institute of Science the Apollo 15 landing site and a similar distance northwest of the Apollo 17 site. Three optional landing sites (primary and two backups) were identified. The terrain in these locations is The main scientific instrument on board the Israeli composed of material characteristic of ancient mare Beresheet spacecraft, the SpaceIL Magnetometer surfaces – large, dark basalt plains resulting from (SILMAG), has now been successfully turned on in long-ago volcanic eruptions – on which successful space and data returned to Earth. After its landings have been made (most recently Chang'E 3 successful launch, Beresheet is circling Earth on and 4). "Lunar magnetism has been an enigma for its journey to the Moon. Prof.
    [Show full text]
  • Arxiv:0706.3947V1
    Transient Lunar Phenomena: Regularity and Reality Arlin P.S. Crotts Department of Astronomy, Columbia University, Columbia Astrophysics Laboratory, 550 West 120th Street, New York, NY 10027 ABSTRACT Transient lunar phenomena (TLPs) have been reported for centuries, but their nature is largely unsettled, and even their existence as a coherent phenomenon is still controversial. Nonetheless, a review of TLP data shows regularities in the observations; a key question is whether this structure is imposed by human observer effects, terrestrial atmospheric effects or processes tied to the lunar surface. I interrogate an extensive catalog of TLPs to determine if human factors play a determining role in setting the distribution of TLP reports. We divide the sample according to variables which should produce varying results if the determining factors involve humans e.g., historical epoch or geographical location of the observer, and not reflecting phenomena tied to the lunar surface. Specifically, we bin the reports into selenographic areas (300 km on a side), then construct a robust average count for such “pixels” in a way discarding discrepant counts. Regardless of how we split the sample, the results are very similar: roughly 50% of the report count originate from the crater Aristarchus and vicinity, 16% from Plato, 6% from recent, major impacts (Copernicus, ∼ ∼ Kepler and Tycho - beyond Aristarchus), plus a few at Grimaldi. Mare Crisium produces a robust signal for three of five averages of up to 7% of the reports (however, Crisium subtends more than one pixel). The consistency in TLP report counts for specific features on this list indicate that 80% of the reports arXiv:0706.3947v1 [astro-ph] 27 Jun 2007 ∼ are consistent with being real (perhaps with the exception of Crisium).
    [Show full text]
  • Guide to Observing the Moon
    Your guide to The Moonby Robert Burnham A supplement to 618128 Astronomy magazine 4 days after New Moon south is up to match the view in a the crescent moon telescope, and east lies to the left. f you look into the western sky a few evenings after New Moon, you’ll spot a bright crescent I glowing in the twilight. The Moon is nearly everyone’s first sight with a telescope, and there’s no better time to start watching it than early in the lunar cycle, which begins every month when the Moon passes between the Sun and Earth. Langrenus Each evening thereafter, as the Moon makes its orbit around Earth, the part of it that’s lit by the Sun grows larger. If you look closely at the crescent Mare Fecunditatis zona I Moon, you can see the unlit part of it glows with a r a ghostly, soft radiance. This is “the old Moon in the L/U. p New Moon’s arms,” and the light comes from sun- /L tlas Messier Messier A a light reflecting off the land, clouds, and oceans of unar Earth. Just as we experience moonlight, the Moon l experiences earthlight. (Earthlight is much brighter, however.) At this point in the lunar cycle, the illuminated Consolidated portion of the Moon is fairly small. Nonetheless, “COMET TAILS” EXTENDING from Messier and Messier A resulted from a two lunar “seas” are visible: Mare Crisium and nearly horizontal impact by a meteorite traveling westward. The big crater Mare Fecunditatis. Both are flat expanses of dark Langrenus (82 miles across) is rich in telescopic features to explore at medium lava whose appearance led early telescopic observ- and high magnification: wall terraces, central peaks, and rays.
    [Show full text]
  • Subsurface Geology of Mare Serenitatis and Surround Regions of the Moon As Revealed by the Lunar Radar Sounder On- Board Kaguya (Selene) A
    71st Annual Meteoritical Society Meeting (2008) 5280.pdf SUBSURFACE GEOLOGY OF MARE SERENITATIS AND SURROUND REGIONS OF THE MOON AS REVEALED BY THE LUNAR RADAR SOUNDER ON- BOARD KAGUYA (SELENE) A. Yamaji1, Y. Yamaguchi2, S. Oshigami2, T. Ono3, A. Kuma- moto3, H. Nakagawa3, T. Kobayashi4 and Y. Kasahara5. 1Division of Earth & Planetary Sciences, Kyoto University, Kyo- to 606-8502, Japan (E-mail: [email protected]). 2Department of Earth & Environmental Studies, Nagoya Univer- sity, Nagoya 464-8601, Japan. 3Department of Geophysics, To- hoku University, Sendai 980-8578, Japan. 4Korea Institute of Geology and Mineral Resources, Daejeon 305-350, Korea. 5Information Media Center, Kanazawa University, Kanazawa 920-1192, Japan. Introduction: Subsurface geology of the Serenitatis and its surrounding regions of the Moon was investigated by the Lunar Radar Sounder (LRS) onboard the KAGUYA (SELENE) space- craft. LRS is capable of surveying to depths of several kilometers with a range resolution of < 100 m and a footprint of several tens of kilometers. Mare Serenitatis, a circular Nectarian basin with a diameter of ca. 600 km, is a typical mascon basin with thick mare deposits and the topographic features thought to be the results of mascon tectonics [e.g., 1]. Results: Despite of simple data processing applied to data from each shot, LRS revealed subsurface stratifications. Numer- ous horizontal and subhorizontal interfaces were found under the mare. Most of their reflections were faint, but there were promi- nent ones as well. We compared our results with those by Peeples et al. [2] who reported subsurface layering in the southern part of the region using the ALSE (Apollo Radar Sounder Experiment) data.
    [Show full text]