Farside Names

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Naming the Farside

(Note: this page is under construction)


It took roughly 300 years to finalize an internationally-accepted system of names for telescopically observable features on the Moon's nearside, culminating in the IAU nomenclature of 1935. By contrast, the main outlines of an internationally-accepted system of farside names emerged less than twelve years after receipt of the first vague images of parts of the Moon's hidden hemisphere on October 7, 1959. A system of lettered designations for lesser features was developed by 1982, but not IAU-sanctioned until 2006.


The Moon's librations make it possible for observers on Earth to obtain occassional highly foreshortened views of the lunar terrain for about 10° beyond the mean limb. Although the mandate for the initial IAU naming effort mentions an intention to include features in the libration zones, the published catalog of Named Lunar Formations (1935) listed feature centers in a mean-Earth projected X-Y ("Xi-Eta") coordinate system, which, by definition, is incapable of specifying positions beyond the average limb (at longitude 90°E/W), few such features were included. The exceptions to the rule include Mare Parvum and Mare Novum -- both names due to Franz.

This is not to say early observers were unaware of other such features, the best known example being the dark patch in the southwest that Franz named Mare Orientale (with a center at around 92°W -- and not listed in NLF). Other examples include named south polar peaks, some of which were believed to reside beyond the mean limb, although precise positions were not provided in Named Lunar Formations.

After the issuance of Named Lunar Formations, the search for possible farside features visible from Earth continued. As an example, Wilkins and Moore's book proposes names for a number of craters they believed to have detected with centers beyond 90° longitude, and traces bright ray patterns observable on the nearside to locate the possible centers of several unnamed others too distant to be observed. For the most part, Wilkins and Moore's libration zone features are difficult or impossible to identify on modern maps, and their proposed names have been ignored.

The IAU effectively imposed a moratorium on efforts to add new names in 1955.

Luna 3 and the 1961 IAU Names

The first, rather vague images of a portion of the Moon's farside returned by Luna 3 in October 1959 led to an immediate wish to name at least some of the features visible on those photos. Eighteen of the names proposed in the Atlas of the Other Side of the Moon (prepared by the three major Russian lunar research centers) were approved by the IAU in 1961.

The following graphics (click to see full-sized) illustrate the positions of the Luna 3 features on modern maps of the Moon:

external image thumb_1961_IAU_FarsideNames_LTVT_Clementine.JPG

external image thumb_1961_IAU_FarsideNames_LTVT_ShadedRelief.JPG

The coordinates of most of these features were "checked" (possibly reassigning them to features different from the ones originally intended) in Menzel, 1971. At least one, Montes Sovietici was deleted.

More Baby Steps

As part of their IAU-sanctioned efforts to revise and update the Named Lunar Formations catalog, workers at the University of Arizona's LPL issued a Rectified Lunar Atlas in 1963. It was based on interpretation of Earth-based photos viewed from "over the limb" by projection onto a globe. Of the 68 names attributed to the Rectified Lunar Atlas in Appendix T of Whitaker's book, nine are current IAU names for features with centers beyond the mean limb: Bel'kovich, Cremona, Fermi, Hale, Jeans, Moseley, Planck, Röntgen and Stefan; although the current Fermi, Planck and Stefan are not the same as the vague "features" named in the 1963 atlas -- and several of the features thought, in 1963, to have centers beyond the mean limb are no longer cataloged that way. In addition to the preceding, the name Joliot-Curie from Luna 3 (now known as Joliot) was "clarified" as being a replacement name for the IAU's former Mare Novum.

Competition for Further Names

The uncertainty of many of the initial farside name assignments, and international rivalry, lead to a rather intense competition for farside names, evidenced, for example, at the 1967 IAU meeting, where U.S. and Soviet maps were presented.

The Soviets seem to have been the most aggressive, presenting maps (in the fashion of America's Rectified Lunar Atlas) with their proposed nomenclature already in place. NASA tended to present maps with the features numbered, awaiting names to be assigned by international agreement.

The difficulty of assigning names prematurely, based on the earliest imagery, is illustrated in the following thumbnails (click to see full-sized) :

external image thumb_CompleteMapOfTheMoon_1967_Section_1_English_names.jpg

external image thumb_CompleteMapOfTheMoon_1967_Section_1_sample.jpg

external image thumb_CompleteMapOfTheMoon_1969_Section_1_sample.jpg

external image thumb_LMP2_Oct_1970_sample.jpg

external image thumb_CompleteMapOfTheMoon_ModernIAU_names.jpg

  • Detail from Section 1 of the Sternberg Institute's 1967 Complete Moon Map with cyrillic names transcribed to western script.

Official names: Menzel, 1971

Whitaker's Lettered Craters

NASA RP-1097

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