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Home / Virtual Moon Atlas - Beginner's Tutorial
by Erika Rix 12/03/05 | Email Author

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This will hopefully be a mini series of tutorials for anyone that wishes to brush up on their atlas skills or for those that a

Virtual Moon Altas - Beginner's Tutorial


This will hopefully be a mini series of tutorials for anyone that wishes to brush up on their atlas skills or for those that are just getting starting with using an atlas. My husband and I got our first scope a year ago and there’s been many on CN who have helped me along the way. It’s been a wonderful experience so far and I am very much looking forward to the years ahead.

One of the biggest pieces of advice for lunar observing that sticks in my mind is from Tim2723 who suggested that I start out by observing and locating the mare regions. Piece of cake, huh? Take a closer look…really. Look with your naked eyes. Can you name them all? How about looking through your binoculars? Maybe a bit easier. Full globe view through your scope now. Whoa….what happened? Everything got turned around most likely, didn’t it? And what’s this….shadows are facing one way during the first half of the lunar phase and then they face another on the second half. In fact, they change constantly, distorting the shapes that we know don’t look like that in the books!

Bottom line is that it’s easy to get disorientated, especially when you up the power and can’t get in as much of the globe as you might need to pinpoint the exact features you’re observing. We’ve all been there. We’re all still learning. We are all here to help in one way or the other.

So with that in mind, I’d like to try to create a series of different tutorials to help find exactly what it is we are viewing. This isn’t a project to find the features for you, nor is it a project to take away from your own learning path….but it is a project that may help you get just a bit more out of your atlases by sharing how some of us do it ourselves. The first of this series will concentrate on A Beginner’s Guide to using The Virtual Moon Atlas. Thank you Patrick Chevalley for allowing me to use your and Christian Legrand’s very useful program for this particular tutorial. Many images have been used by taking screen shots of their program. To download the free version of your choice, please visit http://www.astrosurf.com/avl/UK_index.html

Patrick and Christian have come out with new amazing versions of the Virtual Moon Atlas. To run the full VMA Pro Version 3.0 (Oct 25th 2005), you will need at least a 2 Ghz with 512 Mo RAM and an Opel GL 64 Mo video RAM card. Also required: Windows 95/98/Me/NT/2000/XP. It has been reported to work on Mac with Virtual PC and on Linux with Wine. For purposes of this tutorial I have chosen to use the Expert 2.1 version that came out Nov 7th, 2004. I am in the process of upgrading my machine for the newest Pro Version. This is only a beginner’s tutorial and perhaps we can have another one further down the road with all the upgrades.

First thing after downloading your version, it is necessary to set up the configuration.



Have a play with all the tabs to suit your preferences, but above all, enter in your coordinates and time zone. This is particularly important, as it will effect how the moon appears on your computer screen.
Next, you can choose to show the phase and librations on the display tab. The phase option will show the terminator line and darkened areas. This allows quick identification when you’re out on the field because it will show you exactly what’s in the EP for that particular time and date. The libration can also be pointed on the screen towards the favorable libration.



Of course each of the tabs has wonderful options but I’ll leave that for you to play with for now so we can concentrate on the next stage of this tutorial.

On the left hand side of the screen, you’ll see a set of tabs. Click on the Ephemeris and take in all the information that tab has available for planning! If you click “now” it shows you exactly the information for now. Ok, so that was a given. But what’s going to happen a week from now, a month from now. How about a few hours from now? Change the dates and times and see what happens, both in the information section and on the globe. Perfect, perfect, perfect for planning not only this session but for sessions to come. When will be a great libration for Mare Orientale? The Ephemeris section will certainly hold the answer. But how about a session either you or someone else did yesterday or several months ago? Yep, it’s available as well….just make sure you that if you want it to match perfectly you need change the configuration to match the location and how many hours off it was from Zulu time.

At this time, before I go out to observe (or while the scope is cooling down), I scan and plan.

The views you see at the scope are sometimes different than what the globe shows in the VMA program. Ah, but Patrick and Christian have taken that into consideration as well. Look to the left side tabs once again and you’ll see “Tools” & “Set Up”. In tools, you can manipulate the rotation, default orientation, mirror image, or have the celestial pole on top. I’ve set this to match the view I’d have with my LX200 with the diagonal in. It will be a ballpark figure and adjustments can be made with the west and east rotation tabs once I come back in from my viewing session.



As an example the different views I could have, here are several screen shots stitched together.



By setting up the lighting configurations,



I can change the penumbra, diffuse and specula settings to look something like this:



Now I am ready to print a photo of the globe to take outside with me while I observe. This is handy because it allows me to circle features that I am observing, helping to find my way around the moon that night, write notes on it with arrows pointing to specific areas, etc. But I only want the globe, so to ensure I print exactly what I want, I go to Configuration and click on printing to change the desired settings.



Here is an example of approximately an 18.5 day lunation. Notice the terminator is making its way from east to west. Thank you Jeremy Perez for the use of your image that I have flipped, flopped, and labeled.



Now let’s compare this view with a printout of that night’s VMA view.



Hmmm….which view is suited best for my scope?



Let’s see now…first thing’s first.

What maria or noticeable features can I spot? We’ve got three obvious mares along the terminator and one large crater at the bottom that perhaps looks more like a white spot with rays than it does a crater. I can mark on my VMA printout the areas that catch my eye and circle them if I don’t already know these features. But lets say that I don’t know Mare Nectaris, as it isn’t labeled on the VMA printout. I’m going to circle that feature because that’s the area I want to concentrate on for this observation and look it up on VMA later.

Taking out the 25mm and slipping in my favorite 8mm Plossl, I’m narrowing my search and spy many beautiful areas in and around this mare. The view looks more like this sketch that Rich Handy (Kraterkid) has allowed me to use…thank you, Rich. Can you name all the features I have labeled using your VMA program?



And on the VMA printout below:



1. Fracastorius
2. Rosse
3. Theophilus
4. Madler
5. Daguerre

Ok, so maybe that was too easy as it was in a mare region. Let’s try another one. Hiker, thank you very much for letting me use and mark up your image! I’ve already named some of the maria….can you name the numbered features? Assuming that this is the view through your scope, find that view on your VMA program. Have a play with the Ephemeris to find the correct lunation. Then get into the Tools screen to match up the view and rotation.




The view through VMA should look like this:



The trick is finding the largest easiest craters using maria as guides. Zoom in with your EP if you’re at the scope. Have a good look around. Zoom in on VMA and do the same. Count the craters from a well known feature until you reach the feature in question. Examine the features and see if you can spot the difference in the shapes, are there rilles, wrinkle ridges, rays, ghost craters, domes, massifs? All of these little things can make a big difference. Ah….forgot about sizes. Find a crater you know, look up the size of that crater on your VMA program. How big is the ratio of that crater compared to the feature you see? That’s another good way to cross reference.

Ok, now that you’ve had a chance to look up the labeled features and look for all the “little things that make a great difference”, what did you end up with?

Number one is:



And thanks again to Rich, numbers two and three are:



Numbers 4, 5, and 6 are:



Ok, so it’s becoming old hat now. But let’s have a reversal of finding features. Jeremy did this sketch 09/26/04 at 10pm.



He lives in Arizona so that’s roughly –7 hours from Zulu (universal time/UT). If it was at 10pm Standard time for him, that would actually make the date 09/27/04 at 5am. So in the VMA’s Ephemeris section I took into account which way he said was North and West, then changed the rotation in the Tools tab section. It’s along the terminator as you can see in his sketch. So a quick scan along the terminator line in VMA, then zoomed in revealed this:



There are a few other treasures that shouldn’t be looked over while learning the basics of this wonderful program. Each version has a user's manual within the program. To reach it, click on the top tab that says "Help", then click on the Help option in the drop down box. This will bring up the manual which will look something like this:



It is written in a very user friendly way and I have no problems at all finding the answers to my questions as I use the program.

Another helpful tip is that on VMA's link, they have several supporting links to assist as well...even a Yahoo group dedicated to VMA. http://groups.yahoo.com/group/virtualmoon/

As far as other tools to help identify features, there is a photo database that can be utilized (if not in all versions, then at least in a few of them).

Also, if you look on the right hand side of the screen, you'll see the tabs for information, ephemeris, notes, terminator, tools, setup...click on the information tab and for any feature that you are focusing on, an outline of information will become available for it.

Of course all of the information is indeed helpful and appreciated (believe me when I say that I read every bit of it and use that information to study from or for other resources that they list like Rukl and Woods). But for those of us wishing to have photos to back up what we may have seen compared to the globe on the program, there are Lunar Orbiter photos available on the links provided for those specific features. Scroll down through the outline and towards the bottom you'll see links for these photos (on this thumbnail, they are highlighted in blue).



If I click on the first one, it will bring up a site for the Lunar and Planetary Institute. I can then click on the photo number that I chose from VMA and this link will pop up for the corresponding photo: http://www.lpi.usra.edu/resources/lunar_orbiter/bin/info.shtml?335 There are usually several of these you can choose from to help with identification and all you have to do is click on the thumbnail that pops up from that link and it enlarges, allowing you to soak in all the details.

As you most likely already know, you can also add notes for the features you observe directly into the program....and this would also be very handy directly on the field!



Christian Legrand has stated that there are three stages of lunar observing, quoted below...

"1) You begin. You want to DISCOVER the Moon. You have to recognize the Moon orientation and the place of major features. That's the goal of the "light" (for slow computers) and basic versions. (That was also the goal of the book I have written with my other friend Jean Lacroux "Discover the Moon" published by CUP).

2) After that first step, you want to EXPLORE and know more about the whole Moon and that is existence reason of the "expert" version with its improved databases and it's GOTO possibilities if your scope can use them.

3) Without any doubt, your next step (after several years) will be to STUDY the Moon and that's why we have just released the "pro" version with all its scientific data."

I believe this is a wonderful structure to concentrate on as we develop our understanding of the moon. And how wonderful it is that we have the resources to help us through our journey!

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