Devoted to the Study of Earth’s Vol. 29 No. 3 fall 2010 SELENOLOGY The Journal of The American Lunar Society . Selenology Vol. 29 No. 3 - Fall 2010

The official journal of the American Lunar Society, an organization devoted to the observation and discovery of the earth’s moon

TABLE OF CONTENTS: We Need Your Participation! Determination of A Feature's Vertical Profile ...... 2

Spectroscopy: A How-to For Amateurs ...... 12 This journal showcases the work of American Lunar Society members. Although Selenology is Tidal Heating In the Earth-Moon System...... 13 always interested in articles, we are running low on photographs and drawings/paintings of the moon. Dyonisius ...... 15 Share your work. Encourage your fellow lunar enthusiasts! And you don't need to be a member to get published, so if you have friends who have been reading your issue, encourage them to submit their work. COVER: Send emails to: [email protected]. Regular and Region by Howard mail should be sent to: Eskildsen, Ocala Florida, USA, Selenology 2009/10/26, 00:09 UT, Seeing 6/10, 1807 S. Spring Ave. Transparency 5/6, Meade 6” f/8 Refractor, Sioux Falls, SD 57105. 2X Barlow, DMK 41AU02.AS, W-15 Yellow and IR Block Filters

Selenology, Vol. 29 No. 3, Fall 2010. A publication of the American Lunar Society. President: Steve Boint; Vice President: Francis Graham; Editors: Steve Boint, Raffaello Lena. Web site: http://eselenology.offworldventures.com/ ALS MEMBERSHIP http://amlunsoc.org/

Joining the American Lunar Society is simple. Our only requirement is that you are interested in lunar Copyright © 2010 by the American Lunar Society and individual authors; all rights reserved. observation or studies. Once a member, you will receive our journal, Selenology. To become a member, mail a letter to the address below with a check for $15 US (all countries). Please make check payable Send manuscripts, general observations, photographs, drawings and other correspondence to: to: American Lunar Society. Please include both your e-mail and snail-mail addresses. Steve Boint, Pres. ALS, 1807 S. Spring Ave., Sioux Falls, SD 57105 E-mail: [email protected] Andrew Martin, SFO Send changes of address to Andrew Martin at [email protected] 722 Mapleton Rd, If you don’t have e-mail, send them to Steve Boint Rockville, MD 20850 To subscribe to Selenology, send $15 US to Andrew Martin, 722 Mapleton Rd, Rockville, MD 20850 Make checks payable to: American Lunar Society Questions about your membership or subscription? E-mail: [email protected] Page 2 Selenology Vol. 29 No.3 Fall 2010 Page 3

(free) software is available for this. Registax (http:// error introduced during the mosaicing process. 4) www.astronomie.be/registax/) is free and excel- And the most important rule: DO NOT REFOCUS Determination of A Feature’s Vertical Profile lent. Although a step-by-step isn’t possible where OR TURN THE CAMERA IN THE FOCUSER Accomplished On A Budget software differs, a few guidelines are possible. 1) UNTIL ALL SHOTS FOR THE MOSAIC ARE By Steve Boint Whatever settings used on the frames captured COMPLETED! Failure to follow this rule will ren- for the mosaic should be identical for all video der accurate mosaicing impossible. sequences taken and they should all be processed in Mosaicing is necessary in order to get a good Doing actual lunar research needn’t be be identified later at the measuring stage by find- exactly the same way (frame capture software usu- look at the feature, especially if it is long and restricted to those with telescopes and cameras ing the image which gives the greatest crater depth. ally includes tools for sharpening and changing the extends off of one frame. It also is necessary if costing thousands of dollars. Nor does a person Crater rims as seen from the outside and mountains contrast of the finished frame). Varying techniques publication is your goal, since photos of a feature need to live in an area with perfect skies. When are easier to work with, but they too have their on frames will make the mosaic look bad later. within its larger context help the reader locate the my wife and I first moved to this corner of South requirements. The shadow of the feature must fall Do not add too much sharpening or contrast since feature and understand its topographical and geo- Dakota, the skies were wonderful, but the climate on relatively flat terrain. A rise or fall in the terrain these will make the final mosaic look amateurish. logical surroundings. Luckily, I inherited an old has changed. In the last ten years the jet stream where the shadow tip falls will warp the results. Gentle grays carry more data than do high-contrast version of Adobe Photoshop for my image pro- has often parked just to the south of us, lining up Also, the longer the cast shadow, the more precise images. I process the darkest part of the mosaic cessing. For those without Photoshop or the desire overlapping high and low pressure areas on the the data will be. first since the high- to spend huge ecliptic. This makes the air too wobbly for good I find it easiest to spend an hour or more taking shadow areas gen- amounts of money photos (when it isn’t cloudy). On the other hand, videos of the terminator region (where the shadows erally look the best. on software, many I teach and South Dakota ranks 51st out of the 50 are much longer than the daylit areas) and then Then, I use the freeware graphics states (that’s the honest statistic and I can’t give a later, upon viewing the videos, determine my target same settings on all programs are avail- definite interpretation of the numbers) in teacher for measurement. It would work equally well to do other frames. As a able. Photofiltre is pay. This means my telescope is an old ten inch a detailed live observation in order to determine rule of thumb for one of the best and f/4.5 Newtonian whose focuser is held in place the target feature and then take only video of the processing the first is easily findable with duct tape and a bungee cord. It doesn’t track. region chosen. Either way, be sure to record either (darkest) frame, I using Google. Its mirror has large areas of tarnish. My camera the start or end time of the video sequence in its minimize the white An easy way to is an old Toucam Pro with a chunk of something file name. I use a separate folder with the date and in the image so mosaic is to paste stuck on one corner of the CCD chip. I won’t be then for individual files I record the end time (sans that only a small all the images into getting on LPOD soon. Still, I have found a way to colon): 1025cdst. I convert to universal time later. amount shows, one document, do interesting lunar research determining the pro- I’ve learned through experience that I’ll need Figure 1: I decided to produce a profile of the mountains north perhaps a glint off each as a separate files of lunar peaks which have not been previously to have at least 100, preferably more, frames of the of Gay-Lussac crater as an example. This is a mosaic of many of one peak. 2) layer. Then, set the measured in detail. feature on the avi taken by the webcam. Since my images taken by me on 04/27/2007 at 1:38 - 1:45 UT using Make a separate darkest one on one The method involves: 1) acquiring a useable telescope doesn’t track a feature, therefore requir- a 10" Newtonian, f/4.5, 2x Barlow, and a Philips Toucam set of images for edge of the docu- photo and determining the feature to measure, 2) ing me to let the moon move across the field of my Pro II. Each image which made up the mosaic was made the actual research. ment. Next, change measuring the feature, 3) graphing the results, 4) telescope, I need to give lots of leading and follow- using Registax by stacking 100 frames. Latitude: 43.5293 N. This is necessary the transparency publishing the results. This article will look at each ing space on the video. Generally 50 frames before Longitude: 96.7313 W. because sharpening of the layer which of these steps in turn. the image comes on screen and 50 frames after the image or chang- overlaps the previ- the image leaves the screen is sufficient. Since ing its contrast can negatively effect the measure- ous one to 50%. Drag it into place. Use the arrow Acquiring a useable photo and determining the the terrain surrounding the target feature plays a ments done later. Since the measurements will be keys for fine movements. Once it appears to be feature to be measured large role in interpreting results, I try to take video primarily on the shadow cast by the feature, length- placed correctly, return its transparency to 0%. In order to produce a profile of a lunar feature images of the moon immediately above and below ening the shadow can ruin results. For the actual Most image manipulation software has a way to by using the shadow method, some very specific the path which contained my feature. It is also research frames, use as little enhancement of the toggle layers on and off for viewing. Using this, criteria must be met in choosing the feature. If a valuable to leave plenty of overlap between the image as possible. Endeavor to make the images rapidly click the layer you have been working with crater’s rim as seen from inside the crater is the tar- recorded paths which helps with positioning in the look like they did during live viewing through the on and off while examining the overlap area. If a get, the shadow of the rim must fall across the low- final mosaic. telescope. 3) As much as possible, on the research shimmy appears, move the layer slightly to make est spot in the crater. For large craters, this may be After securing the avi’s, individual photographs frames keep the peak whose profile is sought and it disappear. If the arrow keys don’t allow for fine readily observed. However, smaller craters require must be produced from the video. These frames its shadow together on the same frame. This lessens enough positioning, reposition the layer by drag- imaging on a long term basis so that the center can will be mosaiced together later. Luckily, affordable Page 4 Selenology Vol. 29 No.3 Fall 2010 Page 5 ging and start again. Don’t hurry this step. A poorly Try to make the seam disappear. This works best positioned layer will ruin the later measurements if you don’t make a perfectly straight line with the (although slightly less care can be taken in areas eraser and if you have a couple pixel bleed on the merely providing a topographical context and not edge of the eraser (this can often be adjusted, but if actually part of the measurement). Once the layer is your software doesn’t have this option it will still in the proper place, make sure it’s not still transpar- work). ent and then repeat the process with the next layer Don’t get greedy. Once the image gets too light which overlaps the one just completed. If your to show detail, go no further. A beautiful smaller mosaic is more than one frame tall, do this for all image is much more interesting than a large image the frames from each video pass. with ugly or useless areas. Follow this process for both the mosaic to be Once the mosaic is complete save it. Now, flat- measured and the mosaic which will not be mea- ten it and save it again as a jpeg. Save the image sured. that won’t be measured at 300 dpi. Flatten the Can a mosaic actually be undistorted? Probably image to be measured and save it as a jpeg at 72 not. However, any wide-angle shot of the moon dpi. carries distortion from Earth’s variable atmosphere. I have taken wide-angle photos to back which Measuring the feature show features at different relative sizes to each Download LTVT (free at: http://www.anitabon- other—an artifact of dense air bending light more do.org/_HenriksUCLA/historic_jun07/web-content/ steeply than rarified air. The goal in any mosaic jim_ltvt.html) and install it. This will be the major for measurement should be perfection. However, tool for measurement. an end result equal to a single, large-format photo- In order to begin, it is necessary to place the graph is attainable if the proper care is shown. mosaic to be measured into LTVT. To do this, Once the layers are in place, flatten the mosaic accurate lunar topographical coordinates (latitude to be used for measurement. Save it and set it and longitude) are needed for two features in the aside. I find it best to save it with the date followed mosaic. The best place to begin is the LAC charts by the beginning and end time of the taking of the videos from which it was made. I also convert the time and Figure 3: The feature which will be measured should fill the screen. date to UTC at this point. Conversion charts are readily found through provided by the USGS and made available online In LTVT, use the coordinates of these two spots Googling: cst to utc. Here’s one: by the Lunar and Planetary Institute (http://www. to enter your mosaic. When using the LAC map http://home.hiwaay.net/~krcool/Astro/ lpi.usra.edu/resources/mapcatalog/). Perhaps this to get actual coordinates, use a ruler and calcula- moon/gmt/. is a good time to check the Lunar Topographic tor to determine the fraction of a way between Now it’s time to make the other Orthophoto maps available on the same catalog. marked lines and then convert this to decimal form. mosaic (the one which will appear Any feature covered by this excellent series has Entering the coordinates in LTVT in order to cali- in print) presentable. Using the erase already had its topography thoroughly determined. brate your photo are done under File>Calibrate tool, go through the mosaic one frame Avoid these features if you want your topographical a photo. When entering the latitude, below the at a time and erase the seam where it research to be published. Click on the link for the equator is entered as a negative. When entering overlaps with the mosaic beneath it. LTO maps, then click on the link for “references”. longitude, left of the central meridian is entered You shouldn’t need to adjust the con- The map here will tell you whether the feature has as a negative. You will also need to determine the trast on any frames, only the bright- an LTO map of it available. From the LAC maps, Earth-based latitude, longitude, and altitude of the ness (although shouldn’t and won’t choose the one which covers your feature and location from which your photo was taken. A GPS are two different things, still, any download the 150 dpi version. unit will provide this. If you don’t have a GPS, Now, compare your mosaic with the LAC map. Google Maps under satellite photos has a “what’s contrast adjustments will only make Figure 2: Be sure your photograph is positioned in LTVT so that blending future layers more difficult). Find two spots on your mosaic which are easily here” button on the left. It will provide the latitude the terminator crosses the appropriate spot. identifiable on the map. Be as exact as possible. and longitude of your location. Google Maps is Page 6 Selenology Vol. 29 No.3 Fall 2010 Page 7

Choose mouse options (Fig. 4). produced even now. The profile Another box will appear. Choose the will stay the same, each measure- type of cursor with which you can do ment will be adjusted by the same the most accurate positioning. Next, amount once a laser altimeter choose Inverse shadow length mode value is available for any one part (Fig. 5). This mode will let you click of the profile. on the edge of the shadow and then Now examine the northern click on the feature casting the shadow. extent of the feature’s shadow. Like magic, the math will be done and Determine where the shadow a height value will be determined for starts. Examine the southern point Figure 4: Go to "Mouse options". the feature. A word about the shadow of termination for the shadow. method of height determination is in Starting at the north, measure usually correct. Elevation might be best obtained at order here. the shadow length at every point the county registrar’s office or website. Personally, In the shadow method, the shadow cast by a Figure 7: example of a reference point with a line projecting back where the shadow’s cast end I’d ask a neighbor if he could use his GPS at my peak is measured. Given the angle of the observer toward the sun. changes direction. At each point location and provide the coordinates. and the position of the feature on the moon, the most commonly used on crater interiors or on fea- you wish to measure, right click. Next, place your map on the LTVT moon height of the sun in the lunar sky is determined (as tures whose shadow falls on mare material. This will provide a reference point (Fig. 6) with a through File>Load a calibrated photo. Choose seen by someone sitting on top of the lunar peak). Several factors limit the precision of this meth- line pointing back toward the sun (Fig. 7). Follow your photo from the list provided. Double check From this data, the height necessary for the peak od. Obviously, lunar terrain even in the maria is not the line and place your cursor on the spot where that it is in a believable location on the moon. to cast a shadow of the measured length is calcu- perfectly flat. However, a bounty of very flat terrain the shadow begins. Record the height, latitude, and lated. This method gives the vertical displacement is available on the near side of the moon. Minor longitude. During this phase, be very careful never between the measured peak and the position on variations in the lunar surface are not as large a to right click. Doing so will reset the measuring the lunar surface where the tip of the shadow has factor as the imprecision of determining where the process and make it necessary to toss out your mea- fallen. shadow begins and ends. Lunar shadows consist of surements and start over. This is a relative height. An absolute height both umbra (near ) and penumbra (gray) both Once your feature has been measured for height would be reported in distance above or below lunar on the feature end and on the cast-tip end. Which from its most northern measurable point to its most sea level (an arbitrary official radius on a water- of these, umbra or penumbra, to use is not clear. No southern (Fig. 8), right click and choose Display less world). Relative height is the height difference available study has shown one to always be more distance and azimuth from reference point to mouse between one feature and another. This is what we accurate than the other. Which to use? For generat- point (Fig. 9). Then, at the northernmost part of the normally think of when we think of a mountain’s ing a profile, it does not matter within measure- height since it gives the distance from ground level ments of an individual feature—but whichever you to the tip of the peak. However, this method is sen- Figure 5: Choose "Inverse shadow length mode". choose, be consistent. sitive to elevation differences in the lunar terrain In the past, calculation of shadow heights has beneath the fallen shadow. It assumes the terrain is been so laborious that values were determined only If it isn’t, positive and negative values probably flat. Deviations from this will adversely effect the for the highest part of the peak. In these cases, got entered incorrectly in the previous step. The accuracy of the final profile of the peak which will major error would result if the umbra were cho- LTVT globe provides a terminator line. It should be generated. For this reason, the shadow method is sen and the penumbra should have been, and vice go through your photograph in the correct location versa. However, LTVT makes the process simple for the division between night and day (Fig. 2). If it enough that multiple measurements can be made does not, your conversion to UTC was probably at along the length of a complete feature. From this fault and needs to be double checked. a profile of the feature can be generated. Then, Click on your LTVT photo to center it. Enter a once a lunar probe with a laser altimeter provides value of 40 in the zoom box. Click the texture but- an accurate height for any part of the feature, the ton. Adjust the zoom value as needed until the part height of the profile can be adjusted accordingly. of your image which will be measured takes up the Figure 8: The lines where the feature was measured This will allow for extremely accurate profiles to majority of the screen (Fig. 3). will show even as you move on to the next Figure 6: Right click to produce a reference point. eventually be produced and solid profiles to be Right click on the image. A box will appear. measurement. Page 8 Selenology Vol. 29 No.3 Fall 2010 Page 9

government child-safety regulations. At 49, I’m not the page. My ancient version of Excel does this. I this will be a scientific paper, readers deserve to sure how old you have to be before the federal gov- need to measure the graph on my screen and realign be given a reason to care about the feature. A great ernment is no longer interested in protecting you the axes so that they are proportional. Shading place to start is the moon wiki (http://the-moon. from the horrors of spreadsheets. Openoffice.org the area below the line helps with visualization of wikispaces.com/Introduction). On the left of the also has a spreadsheet available. the actual feature. While not necessary, it is pleas- introductory page, under Features, is a group of Design your data table to clearly show your ing. Remember to label the axes and include units. letters. Click the letter which begins the name of measurements, their units, and their coordinates Generally, gridlines can be removed from the graph your feature. If you have chosen an obscure feature (Fig. 11). Science double-checks itself by allow- because the exact measured number is less neces- which does not appear on the list, pick the name of ing a person’s work to be duplicated (or not if the sary that the relationship between the measured the nearest crater. Under the crater’s entry, look for results are faulty), so present the data keeping in points visualized as a profile. However, do include any information about your feature. mind that another person may want to double-check the actual data points as enlarged areas on the line. On the feature page, you will find a choice of your measurements. photographs. These may or may not be helpful to Figure 9: Choose "Display distance and azimuth The goal of this type of research is to produce Publishing the Results you. Still, they are often worth perusing. Next will from reference point to mouse point. a profile of a lunar feature. So, both the vertical Get your data table and profile ready. Using be a set of links to maps. The LRO website and image which will become your graph, left click. and horizontal axes need to have the same units. graphics software, save both as grayscale (unless data are still randomly cataloged and rather sparse. If the feature you are measuring butts up against The spreadsheet is the place to do this. Most lunar you will electronically publish the data in which Certainly that will change with time and the link to another feature which makes further northern mea- features are far longer than they are tall. So, it is case it can remain in color) jpg’s at 300 dpi (the that data may become extremely useful. Although surement impossible, click at the spot on the feature best to have all units in kilometers. LTVT provides standard for print graphics). You may need to use the odds currently are against finding anything which is on the line from the northernmost shadow height data in meters, so set up a column which screen capture to do this. A couple of hints if you pertinent to a particular feature on that website, it measurement. If the feature you are measuring will contain the converted units. There are 1000 do. Enlarge the data table or profile so that it fills should still be checked just in case (http://www. extends down to a point level with the surrounding meters in a kilometer so the formula in each cell of the screen, this will allow for better capture of type. nasa.gov/mission_pages/LRO/news/index.html). terrain, click on the juncture point. Unfortunately, this column should divide the original height value Bold type seems to capture best. Also, make all this point is often not clear. Use the LAC map and by 1000. lines in the table and profile quite thick. They will careful study and then click on this capture better. As the final touch on the jpg’s, make point. Its height will be zero. Record sure the profile is not wider than inside the margins the latitude and longitude of this in the journal in which you will publish the data. If point. Moving down the feature in you need to shrink the image, make sure the type as straight a line as possible given does not become so small that it is unreadable. If the feature’s shape, a line chosen so this is a problem, go back to the original data table that it is perpendicular to the lines or profile and enlarge the font and try again. drawn from the shadow and so that The profile is best presented using the image it always falls on the feature (Fig. mosaic designed for this and set aside earlier. It 10), record the distance from the should show no seams and be sharpened as much northern reference point that corre- as possible while still looking good. Indicate with sponds to each shadow measurement a line the north/south path on the feature where the made. Record the latitude and longi- measured shadows originated and to which you tude of the southernmost measured measured the shadow length. Attach the profile point on the feature. on side, top, or bottom of this image—whichever Figure 10: Measure the distance between your measurements on a looks best. If you do not have the software neces- Graphing the Results line extending down the feature and perpendicular to the lines which sary to join the profile and image, keep them as Enter the recorded data into stretch toward the sun. separate files will separate captions (Fig. 12, 13). software which can graph the result. Do not add captions to the image but keep them as Google Docs provides spreadsheet and graphing The graph of the data needs to show the fea- a separate word processor file. capabilities for free—or so I’ve been told. I tried ture’s profile, so be sure that the vertical and hori- While the profile is the main part of your pre- to access it for this article, but a glitch in their zontal axes are proportional. Some software auto- sentation, background information will flesh out Figure 11: height measurements for the mountains programming (you have to register to use their matically adjusts the axes so that they stretch across the feature and make it interesting. Even though north of Gay-Lussac crater. aps) locked me out as too young according to new Page 10 Selenology Vol. 29 No.3 Fall 2010 Page 11

they give the direction the shadow fell or the date and time of the photo measured. This severely limits the value of the measurements. Finally, be sure to check the links to LPOD. If the feature you have measured appeared on the Lunar Photo Of the Day, the explanation provided is often very pertinent to any discussion of topogra- phy. The next site to check is the Clementine online at the USGS Map-a-Planet site: http://www.mapa- planet.org/explorer/moon.html. When considering which map to choose on the left hand sidebar, the little “i” gives information about the map (including essential things like the key to what col- ors mean). Some minor absolute height information can be gleaned from these. They are exceptional at elucidating min- Figure 12: The white line indicates the position on the feature for which a profile was generated. eralogy of the region. [See the following The site also contains camera images with explana- Check out the wealth of information on the wiki review of Selenology Today’s issue on tions and with luck one of the images may involve page. Often, one or several researchers will have spectrography.] your feature. The captions are usually very infor- already provided a single height for the feature. The final stage of research should mative, so it’s worth checking these too. This should be reported in your article. It should involve doing a web search for other The site most useful at this stage will be the also be mentioned that unless the height was deter- articles concerning the feature measured. geologic map. When checking the geologic map, mined by laser altimeter, the accuracy of the height Usually little or nothing else will be download the 150dpi version. Lower resolution is probably no better than plus or minus ten per- found, but sometimes other research is loads faster, but it becomes impossible to read the cent. Measurements using high resolution photos available. fine notes on the map and the ledger. Any informa- of lunar probes have a higher level of accuracy. Actually writing the article isn’t as tion explaining the shape or formation or composi- However, one shortcoming of these measurements difficult as it sounds. When I’m having tion of your feature will be useful for writing the has been that they often do not specifically list the difficulty getting started with a project, I article. latitude or longitude of the point measured, nor do use speech recognition software. Speech Figure 14: detail of the USGS Geological Map of the recognition software allows a person Copernicus Region. Although my photograph suggests the to speak into a microphone and have mountains are ejecta from Copernicus, the map reveals that the words outputted as text—kind of a upon close examination through better images, it is actually secretary in a box. Just pretend you are part of the Sulpicius-Gallus Formation. It is volcanic in origin. explaining your research to a high school student. Depending upon the journal in which you wish abstract to publish, there are a set number of expectations a one or two paragraph summary of the research and beyond that much latitude. Generally, publica- and its most important conclusions tions fall into two categories: rigid scholarly format introduction Figure 13: profile of the mountains north of Gay-Lussac crater as seen from the west. Absolute variation and open format. Let’s take the scholarly format explain why your research is important. Provide in height is plus or minus 20%. Relative variation in the profile shape is 10%. Horizontal variation in the first. Scholarly articles generally follow this outline: the geological background of your feature here. profile is 5%. Page 12 Selenology Vol. 29 No.3 Fall 2010 Page 13 This is where the lack of available research on conclusion Tidal Heating in the Earth-Moon System the topography of your feature should be men- give the data collected and the profile produced. Tom Powell tioned. Include a one or two sentence explana- tion of your own research. For a journal like Selenology which has a more On a clear night the lunar maria provide an understood at the time ultimately led to the belief open format, the abstract can be skipped and the abundance of detail for observation. All of these that tidal heating was insignificant in comparison to method order of presentation varied. The article does not interesting features visible on the maria can eas- isotopic heating and the heat of accretion [8]. This explain the difference between relative need to be broken into the four sections listed ily lead to speculation on the origin of the maria led to a general loss of interest in tidal heating in and absolute heights and why relative heights above. However, the same information is given. themselves. There have been some creative origin the Earth-Moon system and undermined confidence are best given as a profile of a feature. Give a What about references? A reference should hypotheses proposed over the years. The ancients in the established models of lunar capture [9]. little background on how shadows can be used be given for each bit of information culled from saw the maria as lunar oceans; pre- thinking It was not until Voyager was approaching the to determine relative heights. Explain how somebody else’s research. LTVT should be end- included the belief that the maria were great seas Jovian system that a paper by Peale, Cassen and LTVT was used. Provide a description of pos- noted. There are different methods of doing this. of dust [1]. There is a hypothesis that the maria are Reynolds (1979), predicting that significant tidal sible sources of error and the variation possible APA style is in wide use. Handbooks are available giant melt pools resulting from the impacts that heating should be found on Jupiter’s moon Io, within your measurements. Horizontal error can at many bookstores. Software is also available to formed the great lunar basins in which the maria that this perception began to change [10]. To the be determined by going back to LTVT and the format endnotes automatically (http://www.neil- primarily lie [2][ 3]. The most widely accepted surprise of many who had thought Earth was the image and choosing Display distance and azi- stoolbox.com/bibliography-creator/index.htm for hypothesis is that the maria formed as a result of only volcanically active planet, Io was found to be muth from reference point to mouse point. Then, one example). This should take away some of the a combination of general heat left over from plan- even more volcanically active than Earth. It was measure the north/south length of the feature. difficulty in producing them. etary accretion and isolated pockets of remnant concluded that tidal heating was the heat source for Then, since it is difficult to determine where the Finally, most journals have writer’s guidelines isotopic heating. The heat of planetary accretion Io’s volcanism. Io’s tidal interaction with Jupiter feature actually begins, set a reference point at available online. Read them and follow them, is thought to account for a 200-400 km deep melt- and the other Galilean produces gravita- the furthest north point where the feature could especially in regard to length. And always run ing of the lunar surface, thus explaining a magma tional interaction which heats Io. Actually three possibly be said to begin and then move the spellcheck. But don’t rely on it. Proofread your ocean event and the resulting lunar crust. The mare of Jupiter’s four Galilean moons are in a Laplace cursor south until you reach the point where it article since incorrect usage of words like “to” and basalts, however, have unique compositional signa- resonance with Ganymede orbiting once, Europa is obvious the feature has begun. Divide this “too” is not caught by spellcheck. A great guide for tures which indicate that they originated by partial twice, and Io four times in what amounts to seven distance by the length of the feature and convert punching up an article is “Elements of Style” by melting in magma chambers presumably heated by earth days. It has since been discovered that tidal the decimal to a percent. Report this as hori- Strunk and White (very short and very good). localized concentrations of radioactive isotopes [4]. heating is a rather common and effective source of zontal variation. For vertical variation, measure It has been pointed out that since the mare heating secondary heating in the solar system [11]. Geysers the height of one spot along the feature twice, References occurred relatively late in lunar history, accretion on Enceladus and Dione, two moons of Saturn, choosing both the longest possible shadow Gerard P. Kuiper, D. W. G. Arthur, E. A. and isotopic heating alone may not be sufficient are believed to be caused by gravitational heating, length and the shortest. Divide the difference in Whitaker, USGS, LAC-58 Copernicus http://www. heat sources for the formation of the maria[5]. as are the subsurface oceans of Jupiter’s moon, these values by the average height of the two lpi.usra.edu/resources/mapcatalog/LAC/lac58/ During the intense scientific effort leading Europa. Tidal heating, resonance capture and damp- shadow length measurements. Convert the deci- Jim Mosher, Lunar Terminator Visualization up to and during the Apollo missions there was a ening of high rates of spinning seem to have played mal to a percent. Tool (LTVT) http://ltvt.wikispaces.com/Downloads robust debate on the possible origin of the lunar a significant part in the evolution of the moons maria. Much of this debate centered on the idea Titan, Iapetus, Ariel, Tethys and Titania as well as Spectroscopy: A How-to For Amateurs that the moon had once been closer to the Earth [6] others. Selenology Today 19 http://digilander.libero.it/glrgroup/ [7]. It was thought that some form of gravitational During the Apollo scientific debate over mare interaction would have occurred during this close origins there was no physical evidence of tidal Seldom do we live to see a classic , but this the material, it requires only a minor familiarity encounter, causing a tidal heating event which pro- heating in the solar system, though it had been year the GLR group published what is bound to be a with spectroscopic studies to produce lunar duced the additional concentrated heating neces- theorized. It was long after the debate concern- long-term classic of lunar reference material. They research of high quality. Ideally, it will become an sary to produce the lunar mare basalts. This idea ing lunar mare formation was over that evidence have digested the material on spectroscopy provided open-source reference and benefit from longterm was primarily associated with the different capture of tidal heating began to be discovered through- by the recent lunar probes and have provided not user revisions to add more and more layers of scenarios of the time and was used to explain the out the solar system. Interestingly enough, there only an excellent discussion of how amateurs can explanation for even easier entry into the field. It dissipation of energy from the moon’s motion in are several features of Io’s volcanism which have make sense of the data, but have also provided deserves this. And, hopefully, GLR will publish order to instill a geocentric orbit and thus argue for parallels to lunar mare volcanism. Both Io and our downloadable software to aid in this task. it as a POD book in the near future so that it can a captured orbit for the moon. Dynamical studies moon are rocky bodies of a similar size and density. Remarkably clear and easy to understand, given become a handy desk-side reference for us all. based on the orbital history of the moon as it was Volcanism on both Io and the moon produces very Page 14 Selenology Vol. 29 No.3 Fall 2010 Page 15 fluid basalts which leave few flow fronts. Io has an implications of the tidal heating found in the solar [16] Touma, J & Wisdom, J. (1998) Resonances [17] Kopal, Z. (1966). On the Possible Origin episodic heating cycle that results in massive heat system is still not well understood, applying what in the Early Evolution of the Earth-Moon System. of the Lunar Maria. Nature, 210 Apri loss in the eruptive phase as heat is dumped onto we do know to the Earth-Moon system could help Astronomical Journal, 115:1653-1663. the surface through basaltic outpourings. This heat explain a long standing mystery — the origin of the loss cools Io, making it less susceptible to Jupiter’s lunar mare flood basalts. tidal pull, thus reducing the effect of tidal heating by reducing the pliability of Io’s rigid body. The References Dionysius heating cycle then begins again; this process has [1] Gold, T (1955) The Lunar Surface. Nature, by Howard Eskildsen resulted in the resurfacing of Io with layer upon 115, 585-604. layer of flood basalts. A similar episodic nature is [2] Ronca, L.B., (1966) Meteoritic Impact and seen in the placement of the lunar mare basalts, Volcanism. Icarus 5, 515-520. Rayed crater Dionysius lies near the west- 50 km further than the radius of the outer circle on with layer upon layer of basalt flows building up [3] Ghods, A. & Arkani-Hamed, J. (2007) ern margin of , not far from my photo (Author not listed 2009). A Clementine kilometer thick deposits [12]. It is noted that the Impact-induced convection as the main mechanism the crater pair of Ritter and Sabine, and south of image shows the dark rays in greater detail (Fig. C). time between flows was long enough to allow for for formation of lunar mare basalts. J. Geophys. Ariadaeus (Fig. A). Another photo of the area The USGS Geologic Map of the Julius Caesar the accumulation of regolith, evidence of the epi- Res. Vol. 112 E03005. reveals the rays and is marked with 20 km, 40 km, Quadrangle of the Moon depicts three medium sodic nature of the mare basalt flows [13]. [4] Taylor, R.S. & McLennan (2009) Planetary and 160 km diameter circles centered on the crater albedo surface units close to the crater and one dark Theory had predicted that Io’s heating would be Crusts: Their Composition, Origin and Evolution. for perspective concentrated at the poles. Surprisingly it was found Cambridge Univ. Press. (Fig. B). The 19 that the heating was actually being expressed in the [5] Grove, T.L. & Krawczynski, M.J. (2009) km diameter cra- equatorial regions of Io. Volcanism on Io is concen- Lunar Mare Volcanism: Where Did the Magmas ter has a slightly trated within 45 degrees of the great circle which Come From? Elements, vol. 5, no. 1, 29-34. asymmetrical is Io’s equator. The lunar maria are also distributed [6] Alfven, H. & , G. (1969). Two bright, continuous about a similar great circle. Generally speaking, the Alternatives for the History of the Moon. Science, ejecta ring nearly lunar maria are located within 29 degrees of a great 165. 40 km in diam- circle which is inclined 6 degrees to the moon’s [7] Kopal, Z. (1966). On the Possible Origin of eter. The bright present equator [14]. The mare distribution may the Lunar Maria. Nature, 210 April. continuous ejecta indeed have originally been produced around what [8] Kaula, W.M. (1971) Dynamical Aspects of appear to extend was the moon’s equator, however it is thought that Lunar Origins. Rev. Geophys. 9, 2, 217-238. slightly farther the uneven loading of the crust with basalt deposits [9] Kaula, W.M. (1973) Dynamically Plausible to the west than would have then caused a reorientation of the lunar Hypotheses of Lunar Origin. Nature Vol. 245 to the east. Both spin axis [15] [16]. The lunar mare distribution October 19. dark and bright is otherwise surprisingly similar to the volcanic [10] Peale, S.J., Cassen, P., and Reynolds, R.T., rays radiate near- distribution found on Io. Thus the lunar mare dis- (1979). Melting of Io by Tidal Dissipation. Science, ly symmetrically tribution could be thought to possibly represent a 203, pp. 892-894. from the crater historical lunar equator during a time of tidal heat- [11] Beatty, K.J., Petersen C.C. & Chaikin, A and most appear ing [17]. (1999) The New Solar System. Cambridge Univ. to end less than Since the end of the Apollo missions, science Press. 80 km from the has struck out to explore the other planets and [12] Woolfson, M.M. (2000) The origin & crater center, with moons of the solar system. The wonderful discov- evolution of the Solar System. Institute of Physics a few extending eries of this unmanned robotic exploration can be Publish., Philadelphia. slightly farther. applied to the moon to further our understanding of [13] http://www.nasa.gov/topics/moonmars/fea- Wikipedia, how- our closest neighbor. Can our modern understand- tures/apollo15_halo.html ever, describes ing of the manifestation of tidal heating on Io and [14] Ward, W.R. (1975) Past Orientation of the the rays as throughout the solar system possibly shed any new Lunar Spin Axis. Science vol. 189. extending more than 130 km from Dionysius and Region by Howard Eskildsen, Ocala Florida, USA, 2009/10/26, light on the pre-Apollo thinking about the origin of [15] Melosh, H.J. (1975) Mascons and the 00:09 UT, Seeing 6/10, Transparency 5/6, Meade 6” f/8 Refractor, 2X Barlow, DMK the lunar maria? Though the exact workings and Moon’s Orientation. Earth & Planet. Sci. Lett., 25 the center of the crater, which is 41AU02.AS, W-15 Yellow and IR Block Filters Page 16 Selenology Vol. 29 No.3 Fall 2010 Page 17

unless the impact had excavated completely through the darker layer and covered the halo with deeper bright-albedo material. Remote sensing stud- ies show that this is not the case. T.A. Giguere et al, used spectral analysis, FeO and TiO2 maps and optical matu- rity data based on Clementine UV-VIS imagery to study composition of the crater-related materials (Giguere et al 2005). The dark rays were indeed mare debris with minor amounts of highland material and dark mare materials were identified high in the inner walls of the eastern and southern portions of the crater Map-A-Planet Explorer: Moon—Clementine UVVIS Multispectral Mosaic— (see Fig. C). The bright Dionysius image rays were predominate- albedo unit (Fig. D). The quadrangle portrays the ly highland material medium albedo units as belonging to the smooth with variable amounts of mare components and the member of the Frau Mauro formation to the north, western and northern interior crater walls were of the formation to the west and undifferentiat- highland material. No solid evidence of dark-haloed ed terra material to the south and southwest (Morris craters was found on the adjacent Cayley deposits and Wilhelms 1967). The dark albedo mare basalts either. of the Procellarum group (in Mare Tranquillitatis) It is likely, then, that the impact creating lie to the east and embay the other formations. Dionysius occurred at the junction of the embay- It is apparent that the impact ejected dark-albe- ment of the highland formations by mare basalts do material as well brighter material to form the at the western margin of Mare Tranquillitatis as rays and, since they represent the material from the Dionysius by Howard Eskildsen, Ocala Florida, USA, 2010/01/28, 01:02 UT, Seeing 8/10, Transparency confirmed by the appearance of both formations least depth, both must have been present at or near 5/6, Meade 6” f/8 Refractor, 2X Barlow, DMK 41AU02.AS, No Filters high in the crater walls on Clementine images. This the pre-impact surface. If the darker material had would explain the presence of bright, and of dark, underlain the brighter, a dark-haloed crater (DHC) rays since both bright highland material and dark might have been expected. However, the material mare material would need to be present near the nearest the crater is bright so it could not be a DHC pre-impact surface to be scattered as light and dark rays over the surrounding terrain. If mare basalts References: were buried beneath the brighter formations, it Author not listed, 2009. Pitatus (crater), would be likely that some craters would excavate Wikipedia, URL: http://en.wikipedia.org/wiki/ Dionysius_(crater), (last date accessed, 29 June through the bright layers to reveal the dark basalt 2010). beneath and form dark-haloed craters. Therefore, Giguere, T. A., Hawke, B. R., Gaddis, L. R., the absence of distinct dark-haloed craters argues Blewett, D. T., Lucey, P. G., Peterson, C. A., Smith, against extensive cryptomare deposits (mare basalts G. A., Spudis, P. D. and Taylor, G. J., 2005. Remote buried under the brighter highland formations) Sensing Studies of the Dionysius Region of the Moon, LPS XXXVI, Abstract #1092. beneath the Cayley and other formations, but does Map-A-Planet Explorer: Moon- Clementine not preclude some minor interbedding of the bright UVVIS Multispectral Mosaic—Dionysius Image and dark layers. Morris, E. C. and Wilhelms, D. E., 1967. Though it is of small size, Dionysius reveals a Geologic Map of the Julius Caesar Quadrangle of great deal regarding the secrets of the Moon. the Moon, USGS. http://www.lpi.usra.edu/resourc- es/mapcatalog/usgs/I510/

Detail from Geologic Map of the Julius Caesar Quadrangle of the Moon by Elliot C. Morris and Don E. Wilhelms, 1967 http://www.lpi.usra.edu/resources/mapcatalog/usgs/1510/