by Jeff Medkeff
Lunar Geology for the Observer
Regional Guide:
Appendixes:
How To Use The Features and Regions Pages:
Each page begins with the name of the feature or region covered by the text, followed by the position. Following that are three time-of-day indicators, so the top of each page looks something like this:
Alphonsus
3° W, 13° SSunrise: 3° (Spring)
Noon: 93° (Winter)
Sunset: 183° (Early Autumn)
These are interpreted as follows:
The title of the region or feature generally is after the dominant topographic feature in the region. Below this is the longitude and latitude of that feature or of the general center of the region covered.
Sunrise for this region occurs at approximately 3° colongitude - this can be looked up in an ephemeris or computed in your star charting software. The time of year during which the moon is best observed at this colongitude is springtime. Seasons are given so that this guide can be hemisphere-independent. For example, sunrise over Alphonsus occurs at 3° colongitude (approximately first quarter) and the moon will be highest in the sky, while at first quarter, during your spring season - this is true whether you are in the northern or southern hemisphere. Similarly, noon over Alphonsus occurs at 93° colongitude, and this phase is highest in the sky during the winter. Co-incidentally, this is just about full moon, but a feature's local noon and full moon occur at different times for features on other parts of the globe. Finally, sunset over Alphonsus - for you early morning observers - occurs at about 183° colongitude and the best season to watch this is during early autumn. During the early autumn, the moon will be high in the sky when the sun is setting over Alphonsus. So this header area serves as a quick-reference guide to the best observing conditions for the given feature or region. This doesn't mean, of course, that you shouldn't look during other periods.
As you begin to read through the text, you will notice that certain feature names are given in bold, others in italic, and others are not set off in any way. This is a code. Names in bold, such as Alphonsus, indicate that the name is IAU approved lunar nomenclature that you should have no trouble finding on any modern chart. This also serves to draw the eye quickly to the place in the text where a specific feature is first mentioned, if you are scanning to reference something specific. Names in italics, such as Rima Alphonsus I, indicate that the name is in fairly common usage, is current observer slang, or else appears on a few charts (particularly the LAC base charts, which are heavily used by the author), but that the name is not IAU approved and therefore not something that you will normally find on charts, nor is it something you can expect all observers to know about. After the first mention of a name, the bold and italic conventions are dropped to promote easy readability. There are also some feature names that are not bolded or italicized - these indicate terms used mainly by lunar geologists, and these are not IAU approved. The exceptions to these rules are due to errors and forgetfulness.
Everything else should be self-explanatory, but drop me a note if you have questions, corrections, or comments.
Acknowledgements:
These notes would not be possible without the generously-provided editorial services of Bob Kuberek, who rescues me from clumsy composition, grammatical goofs, opaque text, and other embarrassing gaffes in the "final" versions of these pages. (I don't inflict things identified as "under construction" on him.) However, I've not adopted all of his suggestions, so any remaining problems are my own fault.
Tracy Wilson is presently the premier lunar sketch artist in the United States. These pages are rendered much more attractive and valuable thanks to the presence of Tracy's sketches. He has generously given me permission to use his exemplary work here; have a look at the Alphonsus page for the first offering.
Want to contribute a sketch or image to one of these pages? Contact me.
References:
General references are below; additional references are included on the feature or region pages. The works below are cited most frequently by their authors' last names.
Goodacre, Walter; The Moon, Pardy & Son 1931
Heiken, French, Schmidt, et al; Lunar Sourcebook: A User's Guide to the Moon, Cambridge University Press 1991
Kuiper, Gerard P., Strom, Robert G., Whitaker, Ewen A., Fountain, John W., Larson, Stephen M.; Consolidated Lunar Atlas; Lunar and Planetary Laboratory 1967
Mutch, Thomas A., Geology of the Moon: A Stratigraphic View, Princeton University Press, 1970
Melosh, H. J.; Impact Cratering: A Geologic Process (Oxford Monographs on Geology and Geophysics; no. 11), Oxford University Press 1989
Wilhelms, Don Edward, The Geologic History of the Moon (U.S. Geological Survey Professional Paper 1348) U.S. Gov't Printing Office 1987
Wilkins, H.P. & Moore, P.; The Moon, Faber & Faber, 1955
Schultz, Peter H.; Moon Morphology
Taylor, Stuart Ross; Lunar Science: A Post-Apollo View
This project has made liberal use of NASA's Astrophysics Data System Abstract Service.
This project has made use of NASA imagery.
Jeff Medkeff's home page.
Jeff's astronomy pages.
Copyright © Jeff Medkeff, 2002, All Rights Reserved.