Keeler (lunar crater)

{{Short description|Crater on the Moon}}

{{About|the crater on the Moon|the Martian crater|Keeler (Martian crater)}}

{{Infobox Lunar crater

| image = Keeler crater 2075 med.jpg

| caption = Lunar Orbiter 2 image

| coordinates = {{coord|10.2|S|161.9|E|globe:moon_type:landmark|display=inline,title}}

| diameter = 160 km

| depth = 3.0 km[http://www.lpi.usra.edu/resources/mapcatalog/LTO/lto85c1_1/ LTO-85C1 Plante] — L&PI topographic orthophotomap

| colong = 200

| eponym = James E. Keeler

}}

Keeler is a large lunar impact crater that lies on the Moon's far side. It is connected along the eastern edge to Heaviside, a walled plain of similar dimensions. Keeler, however, is the younger of the two formations, with more clearly delineated features. To the northeast of Keeler is the smaller crater Stratton, and to the northwest lies Ventris.

Image:Keeler crater AS10-32-4823.jpg]]

The outer rim of Keeler is roughly circular, with a straight segment where it is joined to Heaviside. The northern portion of the rim is more irregular, with an outward protuberance to the north-northwest. Portions of the inner wall have a terrace structure, especially along the southern half. Note the terraced walls of the crater. Within the crater interior, Planté lies on the eastern floor, adjacent to the inner wall. There is an interior ridge that runs from about the midpoint toward the west-southwest. The floor is generally level, with some areas of irregularity to the south. A few small craters mark the interior plain.

Measurements with the electron reflectometer instrument on board the Lunar Prospector showed that this crater is one of a number of impact sites that show demagnetization. The low magnetic reading lies at the center of this crater, and the reduced field extends outward to about one and a half crater diameters. Scientists believe that shock demagnetization is the cause.{{cite conference

| author=Halekas, J. S.

| author2=Mitchell, D. L.

| author3=Lin, R. P.

| author4=Frey, S.

| author5=Hood, L. L.

| author6=Acuna, M. H.

| author7=Binder, A. B.

| title=Demagnetization Signatures of Lunar Impact Craters

| book-title=American Geophysical Union, Spring Meeting 2001, abstract #GP22A-11

| date=May 2001 | bibcode=2001AGUSM..GP22A11H

| url=http://sprg.ssl.berkeley.edu/adminstuff/webpubs/2002_grl_23-1.pdf

| access-date=2010-01-28 }}

Keeler is one of the largest craters of Lower (Early) Imbrian age.[https://pubs.er.usgs.gov/publication/pp1348 The geologic history of the Moon]. USGS Professional Paper 1348. By Don E. Wilhelms, John F. McCauley, and Newell J. Trask. U.S. Government Printing Office, Washington: 1987. Table 10.2.

The crater was named after American astronomer James Edward Keeler by the IAU in 1970.[http://planetarynames.wr.usgs.gov/Feature/2976 Keeler], Gazetteer of Planetary Nomenclature, International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN) Keeler was known as Crater 302 prior to naming.[http://www.lpi.usra.edu/resources/mapcatalog/LunarFarsideCharts/LFC-1%201stEd/LFC-1%202ndEd/LFC-1A/ Lunar Farside Chart (LFC-1A)]Lunar Landmark Locations - Apollo 8, 10, 11, and 12 Missions. NASA technical note D-6082. Manned Spacecraft Center, Houston, Texas. November 1970. Figure 4. A highly eroded crater that is west of Keeler and somewhat larger than it was designated Crater 300, but it is currently unnamed.

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