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
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
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
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:
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
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
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!