(Free) Lunar Atlas Software

Jack Kramer

In the October 2000 NightTimes, I reviewed the "Clementine Skimmer" computer program which provides a lunar atlas based on images from the Clementine spacecraft. Another program called "Virtual Moon Atlas" has become available for downloading from: http://www.astrosurf.com/avl/UK_index.html Like Clementine Skimmer, Virtual Moon is freeware. You'll be amazed at what you can get for nothing!

The basic Virtual Atlas uses a high quality textured drawing of the moon. It also makes use of images taken by various spacecraft, mainly the Lunar Orbiter, but you can download pictures from Clementine, Apollo, and others, plus the Consolidated Lunar Atlas. This allows you to home in on a high-resolution image of a particular feature. Overall, the Lunar Orbiter image quality is somewhat better than the images in the Clementine Skimmer program. The process of downloading the basic Virtual Moon software is fairly quick, unless you also want more images from spacecraft - then it takes awhile. (But definitely get the Lunar Orbiter images!)

I found Virtual Moon easier to use than Clementine Skimmer owing to the distortion-free, more legible basic lunar globe. Another advantage is that the moon is positioned as you see it from your observing point on the Earth. In other words, it shows the current phase and libration of the moon, so you will know which features are on the limb and terminator. Clicking on a feature brings up its name, along with some useful information about the feature and observing suggestions. In the example here, I've clicked on the crater Gassendi. You can then zoom in to get a larger view. The above image is a portion of the Gassendi area at full zoom. Notice that the image is somewhat fuzzy, so if you want a sharp, highly-detailed image of the feature, clicking on the Picture tab brings up a box with the Lunar Orbiter image, as shown below. This image can also be zoomed so as to better inspect certain parts of the feature. The Lunar Orbiter images are shown as they appear from the vantage point above the lunar surface (the same as the Clementine images). The "basic" Virtual Moon image, however, shows the feature as it appears from Earth, with the typical foreshortening of features that lie closer to the limb.

A nice option is that in addition to images from various spacecraft, you can include images that you have taken. Thus when you click on Picture, up pops a menu from which to select the picture source, including your own "My Images" folder. Another nice aspect is that it's interfaced with "Cartes du Ciel" (Sky Charts), Patrick Chevalley's planetarium freeware program. (He happens to also be one of the authors of Virtual Moon.) Thus if you click on the Sky Chart button, up pops a sky chart showing the current position of the moon in the sky. Of course, you also have to load "Sky Charts" on your PC if you haven't already done so.

As is always the case, nothing is perfect. One issue stems from Virtual Moon's use of images for named features. While there's an abundance of these high-definition images from different spacecraft, they don't cover the entire lunar surface. Thus if there's a minute feature far-removed from any of the named features, then it's unlikely to be included in a photographic image. On the other hand, because the Clementine Skimmer program uses a totally photographic rendition of the entire surface, it shows all features.

I have both Clementine Skimmer and Virtual Moon Atlas installed on my PC, though Virtual Moon sees much more use. As noted previously, the Lunar Orbiter image quality is better, and you can zoom in on these images without much degradation. One of the long-time "must-haves" for lunar aficionados is the classic volume of the Rukl atlas, which has now been re-published. I've used the old edition of Rukl, but since adopting Virtual Moon, I haven't gone back to Rukl.

As I write this, the most recent iteration of Virtual Moon is Version 2.1, in "Light", "Basic", and "Expert" packs. The latest enhancement is a driver for Go-To mounts. (But do you really need Go-To for the Moon?) Visit the web site to see which type best suits your needs. I've been happy with the Basic version. The authors have an agenda that includes further enhancements to the program. In a nutshell, Virtual Moon Atlas probably has all the features that the serious lunar observer would want in an attractive and easy-to-use package. If you only have room for one lunar program on your PC, I recommend Virtual Moon...and check the web site periodically for any upgrades coming down the pike.

Published in the April 2005 issue of the NightTimes