Introduction to Google Moon
Google Moon is a recently introduced map tool allows the user to conveniently explore the lunar surface with a computer. It was developed by NASA and made available to the public by Google. The purpose of this article is to help the reader become comfortable with its somewhat complex though easy to use web site.
The tool presents detailed information on the Apollo program as well as maps and images of the moon. This discussion is in two parts. The first covers the map tools. The second explains how you can literally follow the Apollo astronauts station by station as they explored and studied the lunar terrain.
You can find this tool through Google by entering the name “Google moon”. (“moon” alone will not work well.) Or your can enter the address directly. It is: http://www.google.com/moon/
Part I - The Lunar Maps
The initial screen is a photomosaic of the moon with the Apollo landing sites marked. The site of the first Apollo landing is pre-selected and the balloon gives a summary of the mission. Select the X to close the balloon. Now you can see flags for all six landing sites.
On the left is a zoom level scale. I will call the bottom cross hatch ‘level 1’ and count up from there. Bottom left is a map scale marker. Since the maps are Mercator projections this is only approximate. Top right is the list of displays provided.
Click on the Visible button to remove the overlays. The display is a photo mosaic of the lunar surface excluding the polar regions. At zoom level 1 the image appears as a band across the middle: the entire image repeated four times.
You will notice that craters are distinct along the top and bottom but not along the equilateral region. Apparently this composite is cleverly composed images all taken at local noon-time. Hence near the poles there are extensive shadows that make craters and mountains clearly visible. In equatorial regions there are no shadows.
Select zoom level 4. The seas or mares are clearly visible as are the rayed craters. Now click the elevation button. This beautiful color map is shadowed to clearly show every detail of the surface.
Go ahead and explore: pan around, change zoom level and switch back and forth between visible and elevation maps. You will notice that the system keeps track of zoom level and location so that these are kept the same as you change your map selection. This gives researchers a power they only could dream of before!
Now select the elevation chart at level 4 and click the chart button. A display will appear the lower right corner. Slide the map if necessary to put the pre-selected chart in the center of the display.
Move the cursor over the display selector and note the red boxes that appear over the corresponding areas of the elevation display.
Again the chart is directly over the corresponding area of the elevation display (or the visible image if you have that as background).
The Topographic Tab
With the topographic tab selected (bold) the chart will show the topography of the area selected. At level 8 the chart text is readable. Note that names are on major craters and most Mares. A grid for latitude and longitude are also provided. Elevation lines are shown but barely readable.
The Geologic Tab
This chart also includes feature names and position information. The chart is quite colorful and represents a code for many types of surface material. One would have to study the margin notes to understand the code. Geologic charts are no doubt valuable for researchers and students but you may want to leave that for another day.
Part II – Following the footsteps of the Apollo Astronauts
At startup Google Moon displays the visible map with each Apollo landing site marked. The Apollo 11 site selected by default but you can select any site using the thumbnails across the bottom or one of the site flags.
Lets stay with Apollo 11 and click the “zoom in” button. This brings up a detailed drawing of the area covered by the astronauts. The area in this case is small since they were moving around on foot and had a very conservative set of goals. Each station is tagged and corresponding thumbnail images lie across the bottom of the display.
Put the mouse cursor over the 12th thumbnail. A label will pop up that reads: “12. Laser Ranging Retroreflector” or LRRR. Click on it and a balloon will appear over tag 12 containing a description and a larger version of the thumbnail image. The scroll bar on the right allows one to read the entire text of the balloon. Click on the image to get a larger full screen image.
Click on the image to bring up the full resolution image. Use the sliders on the edge to move the picture to see any desired portion. Pan over to the LRRR and note the handles on both sides of the device. These are among the many accommodations required to allow astronauts in cumbersome space suits to move things into the proper place.
Close the tab to return to the prior display.
A second kind of image display is the panorama. Click on thumbnail (or tag) 16. Controls are provided to zoom and pan freely over the image. First you can see a rather large crater with a lot of rocky rubble in the bottom. Pan to the left on this image and more craters of various sizes will appear. At the far left you will find the lander craft.
The last feature I will discuss is the “Apollo Lunar Surface Journal”. Click on any thumbnail or tag and pull the balloon scroll bar all the way down. Selecting this bottom entry will bring up the surface journal. The actual text of communications with ground control is recorded here with clarifying information that was added later to complete the story. Here you can also bring up video or audio clips if desired.