By
Marvin W. Huddleston, F.R.A.S.
A.L.P.O. Lunar Recorder: Lunar Dome Survey
Link Removed
kc5le@sbcglobal.net
ABSTRACT
The A.L.P.O. board of directors approved the revival of the Lunar Dome Survey during their annual board meeting in the summer of 2003. The initial LDS program was conceived by Harry Jamieson in the early 1960’s and headed by him when the B.A.A. was invited to join the program, which they did and the joint effort between the A.L.P.O. and B.A.A. lunar sections lasted for around 14 years, ending officially around 1976 due to a decline in interest. The program was again revived in 1987 under the direction of Jim Phillips and lasted until around the mid-1990’s. All told, this program has been one of the longest running programs in the history of the Lunar Section of A.L.P.O.
The revived program will concentrate on cleaning up the existing catalog, classification and confirmation of the objects contained therein, and analysis of the database created in the process. It is hoped that much as in the past the newly revived Lunar Dome Survey will be an international effort.
Introduction
Lunar domes are gentle swellings on the lunar surface that resemble terrestrial shield volcanoes (similar shield volcanoes are also found on Mars). Domes are not difficult objects to observe despite the fact that they are practically invisible at solar altitudes exceeding 8-10 degrees. Under higher illumination, they tend to blend in to the surrounding lunar terrain. Thus, the window of opportunity for their observation is quite narrow. However, most lunar domes are well within the reach of practically any amateur telescope and valuable contributions may be made by just about anyone willing to learn some simple techniques.
There have been a number of theories as to the morphology of lunar domes. These include the possibility that they are surface expressions of laccolithic intrusions. Another possibility, as already mentioned above, is that they are small lava shields (i.e. lava domes). If this is the case, they are the result of repeated extrusions of low viscosity flows.[1] The small scale shield hypothesis seems the most tenable of the current theories, and if this proves to be the case they may be lunar examples of Hawaiian style lava domes. Their terrestrial equivalent differs from their lunar counterpart in that they have much steeper slope angles than the normal lunar dome and probably have a quite different genesis.
Earth based volcanic domes of the cinder cone variety form via explosive eruptions which pile up lava around a central vent. Such explosive eruptions on the moon would, due to gravity differences (lunar volcanism occurred in 1/6th the gravity as that of the earth), would have thrown such material much further, leaving little material which would form the dome around a central vent. Terrestrial domes also form from much thicker lava, whereas lunar domes likely form from Basaltic lavas which are more liquid in nature. Furthermore, lunar dome genesis is more likely a function of much cooler lava than those found on earth. Large scale shields such as Olympus Mons and Launa Loa do not occur on the moon.[2]
Photograph by T.P. Miller in June 1979
Fig. _A___. Volcanic dome atop Novarupta vent, Valley of Ten Thousand Smokes, Katmai National Park and Preserve, Alaska. The dome was erupted from the same vent that expelled about 15 km3 of magma in an enormous explosive eruption in 1912. Note the much steeper slope angle as compared to Lunar Domes.[3]
John Westfall gave us the following definition of Lunar Domes which the newly revived program will continue to adopt as our working model:
Dome: A discrete regular swelling whose major axis: minor axis, when corrected for foreshortening, does not exceed 2:1, and whose maximum slope, not including secondary features, does not exceed 5 degrees. Under high illumination, domes are indistinguishable from their surroundings. Domes may exhibit secondary features, such as pits, clefts, ridges, and hills as long as any single such feature does not occupy more than a quarter of the area of the dome.
Dome Complex: Any object similar to a dome which has two or more contiguous swellings or an irregularly vertical profile.[4]
The study of Lunar Domes can be traced back to the early twentieth century. One of the earliest contributions to this line of scientific research was the observations of the Milichius/Tobias Mayer region by S.R.B. Cook in 1935. At this same time, a drawing of the Hortensius domes by Schlumberger was published in The Moon, by W. Goodacre.
The formal study of Lunar Domes dates to around 1963, when the Lunar Sections of the Association of Lunar & Planetary Observers (A.L.P.O.) and the British Astronomical Association (B.A.A.) agreed to undertake a joint effort in Selenology with the launching of the joint ALPO/BAA Lunar Dome Project. The A.L.P.O. Lunar Dome Project was the product of the dedicated work and leadership of Mr. Harry D. Jamieson beginning around 1960.
An initial catalog was published listing 113 objects. A revised catalog was published in 1992 by the A.L.P.O. Lunar Section which listed 713 objects. In addition to these catalogs, this writer published a revised catalog which listed a total of 607 confirmed and unconfirmed lunar domes on the internet (the first such listing widely available via the net).[5] The best current official catalog appears to be the one available as a part of the Lunar Observers Toolkit mentioned elsewhere in this paper. It will be this work which will constitute the “official” catalog for ALPO purposes. It is comprised of the labors of many people, and is considered by the section as the standard reference for research. Another good work (currently unpublished) has been produced by Bob Garfinkle, F.R.A.S., which lists 702 objects. Mr. Garfinkle has attempted to fix errors and omissions as well as duplications in the 1992 and web based catalogs. Of special value to dome researchers and observers is the extensive remarks column offered in this work.
Lunar Dome research is one avenue available for the Amateur Astronomer who wishes to make truly valuable contributions to the science of Selenology (Lunar Astronomy). The A.L.P.O. has been involved in the scientific study of these elusive objects for over four decades now, beginning with the inception of the joint ALPO/BAA Lunar Dome Project in the mid 1960’s.
The renewed program of Lunar Dome study is deemed as a valuable effort. This renewed study will concentrate on cleaning up the catalog as well as in fully classifying the objects in the catalog using the Westfall Classification System. The revived program will also stress obtaining accurate measurements of the slope angles and diameters of the domes in the catalog. Another primary goal of the revised program will be to undertake the establishment of a digital catalog of Lunar Dome images.
Much as in the programs original inception in the early 60’s, it is desired that the present effort be an international one. Members of the A.L.P.O., the B.A.A., Geological Lunar Researches Group (G.L.R.), American Lunar Society (A.L.S.), as well as all other students of Selenology are invited to partner with us in the effort to complete the work began four decades ago.
The Situation Today
In February of 1961, Joseph Asbrook wrote concerning Lunar Domes: “There is a serious lack of quantitative information about the properties of lunar domes—diameters slope angles, and heights. Such data are helpful in defining what a dome is and essential for subclassification [sic] and meaningful interpretation.”[6] This writer wishes that the situation after forty-two subsequent years of research and study of Lunar Domes has now been resolved and that we have an accurate and fully classified catalog of the domes under study. However, to do so would be an exaggeration of the greatest albedo!
The original catalog of Lunar Domes published as a joint effort between the A.L.P.O. and the B.A.A. Lunar Sections included 113 objects. To this initial catalog, the studies over the past four decades have added approximately 589 objects. So in respect to the numbers of known and suspected objects, much progress has been made. In respect to routine science, however, it appears that little progress has been made, because today little more is known about the approximately 702 objects in the current catalog than was known about the original 113 objects as published in 1965.[7]
This is a curious situation. During the four decade old formal study of Lunar Domes much was done toward the discovery and confirmation of new objects, but little has been done during this same time period to determine the properties and characteristics of the domes currently known. Many of us seem to have been committed to the glory and satisfaction of discovery [the author must stress that in pointing fingers in this he points three at himself for every one pointed at other readers], but few of us seem to be interested in the mundane science behind the original project.
Fig. _B___. Drawing of the Cassini region showing suspected dome by Raffaello Lena, September 28, 2002 at 4:08 UT; 100mm refractor at f/15, 250X. Seeing good. For more information please visit: http://utenti.lycos.it/gibbidomine/cassinidome.htm
The study of Lunar Domes has been viewed by many of us as one of the foremost contributions amateur astronomers can make to the science of astronomy. This program remains as one of the areas in Amateur Astronomy in general and Selenology in particular wherein the amateur astronomer may make a truly valuable and lasting contribution to science. Our generation of Selenologists has the opportunity to leave a lasting legacy in the work we do in our current and future studies of Lunar Domes. In the words of one of the Ghostbusters: “We have the tools, and we have the talent!”
Earlier generations of dedicated Selenologists, particularly in the amateur ranks, were reserved to observation of the moon and its many features with quite modest astronomical equipment. This writer began his LDS studies with a 2.4 inch refractor, when the mean aperture for amateur astronomers was in the neighborhood of 8 inches. We now live in an age when the mean aperture of the amateur astronomer’s equipment is growing (it is now likely to be a mean of 14 inches aperture) almost daily to staggering statistics (one word of caution: this writer has discovered a suspected correlation in the aperture gain of the telescope primary mirror with the aperture gain in his waist over the past 30 years; more scientific study may be necessary before this correlation may be considered a scientific fact). It is common today for an amateur astronomer to attend an event such as the Texas Star Party in the Texas Davis Mountains and have the opportunity to observe with instruments in the 36+ inch range. This writer observes these days with a modest aperture Dobsonian of 18 inches, complete with electronic Goto and tracking ability!
Fig._C__. The author, Marvin W. Huddleston, F.R.A.S., the ALPO Lunar Recorder for the Lunar Dome Survey, with his 18” Starmaster Newtonian Telescope at the Texas Star Party held at the Prude Ranch near McDonald Observatory in May of 2002. This telescope features a superb f/4.3 Zambuto primary mirror and the Skytracker electronic “Goto” and tracking package developed by Rick Singmaster of Starmaster Telescopes.
In addition, the lunar observer of yesteryear had to laboriously plot domes on a chart for observation and study when today this effort is a needless exercise thanks to the Lunar Observers Toolkit written by Mr. Harry D. Jamieson.[8] This software is simply phenomenal in its capabilities, listing domes for observation on any given date and plotting them on a moon graphic showing the nights moon phase as well. Other useful features offered in the Toolkit are such abilities as the computation of accurate heights and depths. Overall, this software is deemed indispensable and unequaled in value to any student of Selenology.
Fig._D_Lunar Map Pro chart of the Copernicus region also showing the crater Hortensius and Tobias Mayer, both regions well known to Lunar Dome Observers. Compare this image with the Fig._F__ taken by Ed Crandall.
Additional software that has become available to the Lunar Observer interested in Lunar Domes in particular and Selenology in general include the commercial product Lunar Map Pro produced by RITI.[9] An example of this software’s charting capability may bee seen in Fig._D_ showing the Copernicus region which includes the craters Hortensius and Tobias Mayer, both familiar sights to Lunar Dome observers. One of the interesting tools in the Lunar Map Pro software is the Surveyor tool. This tool allows the user to mark two locations with their computers curser and with a simple click measure the distance for point A to point B. The resulting computation is given both in Kilometers as well as in Miles; it also gives the Azimuth between the two points. It should be noted by the reader that the accuracy of this method has not been confirmed. However, there is a useful feature in the software allowing the user to specify specific image scaling, which it is assumed would increase accuracy.
Another nice program for plotting lunar phases is Lunar Phase Pro, produced by Gary Nugent.[10] This writer especially likes the real time display format of this software. This software is useful for the observer wishing to keep tabs on real-time technical data such as Libration, Colongitude, Position angles, etc.
Fig._F__. Image of Lunar Domes near Hortensuis by Ed Crandall. Copernicus is visible on the lower right. 10″ f/7 Newt SLX HX 516 CCD camera; 10 June 2003 @ 2:24 UT (S=5/10)
Another improvement we have over previous generations has been recent advances in imaging technologies. Today the amateur Selenologist can, with a very modest monetary investment, perform lunar imaging rivaling the professional astronomer of yesteryear with such instruments as CCD cameras, CCD video cameras, digital cameras and/or inexpensive web-cams.
Fig._G__. The Philips To-U-Cam, one of the many inexpensive web-cams available which is allowing the amateur astronomer to secure high resolution photographs of the lunar surface (as well as planetary subjects such as Mars and Jupiter). The addition of an inexpensive adapter by Steven Mogg[11] (center) turns this simple web-camera into an effective Astronomical Imaging instrument. Meade’s new LPI (Lunar Planetary Imager, right) is a new and exciting product for Lunar and Planetary Imaging. The LPI is shown here attached to a LX200GPS Telescope.
Fig._H_. Image of Mare Serenitatis showing the Bessell region, site of a number of illusive objects (possibly domes) associated with “White Patches.” Also note …. taken by the author; Starmaster 18” f/4.3 and Meade LPI imaging camera. 12/30/2003 UD 00:21:17UT, Colongitude 348.57* Composite of 20 images stacked automatically by the LPI software.
One advantage that our predecessors had over us was the availability of some of the finest lunar atlases of all times. This writer has contacted the University of Arizona Press numerous times in hopes that the Orthographic Lunar Atlas might eventually be reprinted, but to no avail. There were hopes at one time that a digital version might be made available, but this writer has been unable to confirm this rumor. Likewise, the Rukl Lunar Atlas is out of print, leaving our generation with the best equipment in Selenological history but in the worse situation in decades as far as availability of accurate hardcopy lunar atlases for positional work. However, light is visible at the end of the tunnel, as this writer has it on good authority that the latter will be available soon in a reprint edition.[12]
The renewed Lunar Dome Survey will concentrate its efforts on the mundane science of LDS research. Science depends upon accurate data. It will be our mission to take as our foremost responsibility the existing extensive catalog of Lunar Domes and make this catalog an example of some of the finest work ever accomplished by students of Selenology. Our emphasis will not be on the discovery of new objects, though occasional discoveries may be made in the process; rather, our emphasis will be on the classification, measurement, and analysis of the domes in the existing catalog.
Fig._I__. USGS illustration of Volcano Types. Lunar Domes are thought to be the Lunar counterparts of Shield and/or Volcanic Domes. Though their genesis may differ, much is to be learned from studying the terrestrial counterparts.[13]
Many questions remain as to the nature of Lunar Domes, which the renewed program will attempt to answer. For example, what is the correlation between central craters and a domes shape, size and other characteristics? Is there a ratio to central crater size and dome diameter? What are the statistics between circular domes with central craters and those without these craters? Are there correlations between elliptical domes and associated secondary features? What is the relationship between Lunar Domes and specialized secondary features, such as white patches?[14]
The renewed program will concentrate on the following observational data much as it did during the late 1980’s revival of the project. The following is based on a paper by Harry Jamieson’s and is reproduced here for the benefit of those new to lunar dome work:[15]
- Position
Observers should carefully check dome positions and report any errors or inaccuracy in catalog positions.
- Diameter
Measure dome diameters using size comparisons to nearby craters of known diameter. Joseph Ashbrook detailed this method thus: The observation consists in estimating the ratio between the domes apparent diameter and the parallel diameter of the comparison crater. For example, if the crater has a diameter of 10.0 kilometers, and you estimate the domes diameter as .55 of this, the dome diameter is .55 x 10 = 5.5 kilometers.[16] Additional methods may include the use of micrometers or reticle eyepieces.
- Average Slope angle and Height
The moment at which a dome is covered by ¼ black (not grey, which represents grazing illumination by sunlight) shadow should be accurately noted. Average slope angles and heights can be computed at this time because the suns altitude over the dome at that moment may be taken as the domes average slope angle. Given the domes average slope and diameter, the height can be found easily using the Lunar Observers Toolkit negating the complicated calculations necessary in past years. Consult the help file in Toolkit concerning “Lunar heights and depths” for detailed instructions.
- Maximum Slope Angle
This value is equal to the suns altitude when the last trace of shadow is observed at the foot of the dome in the lunar morning. Note that this determination should also be done in the lunar afternoon and that the two values thus found may be different.
- Dome classification (Westfall Classification).
- A dome is a discrete feature, not a part of something else.
- A domes ratio of major/minor axis (corrected for foreshortening) may not exceed 2:1. This is designed to eliminate ridges.
- A dome may not exceed a maximum slope angle of 5 degrees. This definition is designed to eliminate hills and peaks.
- No single secondary feature (cleft, crater, etc.) may occupy more than ¼ of the surface area of a dome (with perhaps the single exception of “White Patches” which have been noted atop some domes). White Patches are largely poorly understood and have been ignored for the most part.
The renewed effort will be quite interested in the study of the various types of secondary features. Data are needed concerning the characteristics and correlations of such features.
The Westfall Classification system is designed to describe the physical characteristics of a dome using a combination of a letters and numbers. Readers should note the addition of a Type 10 secondary feature listed under the heading “Surface Feature type.” The following is a brief outline of the classification system:[17]
Broad Category:
D: Dome
DC: Dome complex (several domes in physical contact (i.e the Rumker complex).
Surroundings:
U: Uplands
W. Maria
UW: Uncertain if Uplands or Maria
Plan: Domes major axis is:
1. Less than 5 kilometers
2. 5-20 kilometers
3. 20-35 kilometers
4. 35 kilometers
Written notes submitted to the Recorder should include size estimations with as much accuracy as possible.
Border:
a) Circular (major/minor axis 1.00-1.25)
b) Elliptical (major/minor axis 1.26-2.00).
c) Polygonal
d) Irregular
e) Too ill-defined to classify
Profile (average slope):
5. Gentle (under 2 degrees)
6. Moderate (2-5 degrees)
Profile-Cross section:
f. hemispherical
g. flat summit (platykurtic)
h. sharp summit (leptokurtic)
i. Multiple summit (more than one summit; but of single type).
f’. Hemispherical (Asymmetric)
g’. Flat summit (Asymmetric)
h’. Sharp summit (Asymmetric)
i’. Complex summit (more than one summit and of different type).
Surface Detail-type:
7. Depression (pit, craterlet, or saucer)
8. Elevation (hill, ridge, or pit)
9. Cleft or Valley
10. White Patch (area of higher albedo than surrounding lunar surface usually located atop the domes location).
0. No observable detail.
Surface Detail Position:
j. central
k. Off-central
m. margin
n. Transversal (cross dome)
p. more than one such feature.
An example of the classification system in actual use might be recorded as DW/2b/6f//7j/9m/8p which translated means: (DW) Dome within Maria, (2b) 5-20 kilometers and elliptical, (6f) moderate slope and hemispherical, (7j) depression central on the dome, (9m) cleft or valley on the margin of the dome, (8p) Elevation – more than one such feature.
It is hoped that many will take on the challenge of helping us finalize the catalog and answer this call to arms! What the reader must understand is that until the catalog is completed and an accurate database established analysis of the objects cannot produce usable date. Taking accurate data such as the Westfall Classifications and analyzing these will allow researchers to analyze the data set and produce an accurate definition based on the data. We need observers dedicated to study of these elusive Lunar Domes.
Selected Bibliography
Ashbrook, Joseph. Dimensions of The Lunar Dome Kies 1 in J.A.L.P.O. 15, NO. 1-2. (Edinburg, Texas: Pan American College, 1961).
Hudleston, Marvin W. Lunar Domes and White Patches: A Correlation Report in Proceedings of the joint WAA-ALPO 1972 Convention.
Jamieson, Harry D. and Rae, W.L. The Joint ALPO-BAA Lunar Dome Project in Strolling Astronomer 18, no. 9-10 (University Park, N.M.: The Association of Lunar & Planetary Observers, 1965).
Jamieson, Harry D. Observing Lunar Domes in JALPO 33, no. 1-3 (Heber Springs, Ark.: The Association of Lunar & Planetary Observers, 1989).
Rukl, Ing Antonin. Personal correspondence dated July 1, 2003.
Schiltz, Peter H. Moon Morphology. (Austin, Texas: University of Texas Press, 1972).
Taylor, Stuart Ross. Domes and Cones in Planetary Science: A Lunar Perspective. (Houston, Texas: Lunar and Planetary Institute, 1982).
Westfall, John E. A Generic Classification of Lunar Domes in Strolling Astromomer 18, no. 1-2. (University Park, N.M.: Association of Lunar & Planetary Observers, 1964).
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[1] Peter H. Schultz, Moon Morphology. (Austin, Texas: University of Texas Press, 1972), 286.
[2] Stuart Ross Taylor, Domes and Cones in Planetary Science: A Lunar Perspective. (Houston, Texas: Lunar and Planetary Institute, 1982), 274.
[4] John E. Westfall, A Generic Classification of Lunar Domes in Strolling Astromomer 18, no. 1-2. (University Park, N.M.: Association of Lunar & Planetary Observers, 1964), 15-20.
[6] Joseph Ashbrook, Dimensions of The Lunar Dome Kies I in J.A.L.P.O. 15, NO. 1-2. (Edinburg, Texas: Pan American College, 1961), 1-3.
[7] Harry D. Jamieson and W.L. Rae, The Joint ALPO-BAA Lunar Dome Project in Strolling Astronomer 18, no. 9-10 (University Park, N.M.: The Association of Lunar & Planetary Observers, 1965), 179-182.
[8] Mr. Jamieson may be contacted concerning his Lunar Observers Toolkit at h.jamieson@bresnan.net His toolkit will be an essential accessory for participants in the newly revived Lunar Dome Survey and is available at very modest cost. This software runs independent of installation CD. One of the numerous great features in the Toolkit is its link feature to the Consolidated Lunar Atlas. The lunar phase display screen also plots all domes in the catalog on a graphic display of the current lunar phase, though the phase is a stagnant display and not a continuous phase updating screen.
[12] Ing Antonin Rukl, personal correspondence dated July 1, 2003. Mr. Rukl reported that his atlas will be reprinted by Sky Publishing Corporation in the near future.
[13] http://vulcan.wr.usgs.gov/Glossary/VolcanoTypes/volcano_types.html
[14] Marvin W. Huddleston, Lunar Domes and White Patches: A Correlation Report in Proceedings of the joint WAA-ALPO 1972 Convention, pgs. 120-121.
[15] Harry D. Jamieson, Observing Lunar Domes in JALPO 33, no. 1-3 (Heber Springs, Ark.: The Association of Lunar & Planetary Observers, 1989), 23-24.
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