The Moon is a substantial satellite almost half the size of the planet Mars. As fortune would have it only one side of the Moon’s surface ever shows toward Earth. However the Moon is believed to be about 4.6 billion years old and thus it has had ample time to aggregate a fascinating landscape, especially as there is minimal weathering or plate tectonics. Using the typical unaided eye the Moon is seen as a large disc with varying brightness across its surface. However with binoculars or telescopes the surface jumps into bright relief and then fine shadows and patterns tell an amazing story that can be just as exciting as Mars.
The story of the Moon includes many great characters. Tycho and Copernicus are great rayed craters dominating the scene. Mare Imbrium and Mare Tranquillitatis provide a smooth, gentle supporting backdrop for smaller understudies. To see any of these in great detail wait for the Moon’s terminus to highlight their features. The terminus is where the sunlight striking the Moon’s surface fades into the shadows of space. As the light and the surface are at an oblique angle the features have strong shadows, making them stand out and enabling estimates of their height and shape. To accommodate this, the guidebook provides charts of the terminus for each day of the lunar’s 29 days cycle. Each chart is oriented in a North-South reference as seen from a small telescope thus making a perfect reference. Extensive adjoining text gives an appropriate description together with some conjectures about formation. All in all the Moon’s story is varied, gently paced and continually varying.
To compliment these charts there are further notes on the Moon relevant to the space enthusiast. Aides to observing are covered in some detail, these being binoculars and telescopes. The Moon’s presumed formation theory and geology add a nice temporal factor. Stellar events such as libations, occultations, ecliptics and eclipses round out this guide for observing the Moon.
I like the Moon Observer’s Guide. It provides an economical and extensive resource for observing Earth’s satellite. For the astronomy addict it may become quickly trivial but for an introduction it is an invaluable aid.
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Review by Mark Mortimer.