Babcock Crater Honors American Astronomer Harold Delos Babcock

Summary: Babcock Crater honors American astronomer Harold Delos Babcock, whose astronomical expertise emphasized solar magnetism and solar spectroscopy.

Detail of Lunar Astronautical Chart (LAC) 64 shows the lunar far side’s Babcock Crater with its two satellites on the northeastern edge of Mare Smythii (Smyth’s Sea); courtesy NASA (National Aeronautics and Space Administration) / GSFC (Goddard Space Flight Center) / ASU (Arizona State University): Public Domain, via USGS Astrogeology Science Center / Gazetteer of Planetary Nomenclature

Babcock Crater honors American astronomer Harold Delos Babcock, whose astronomical achievements included researching solar magnetism and solar spectroscopy.

Babcock Crater is a lunar impact crater in the equatorial latitudes of the lunar far side’s portions of the moon’s northern and eastern hemispheres. Impacts have bombarded Babcock’s eroded rim. The interior floor’s relative levelness results from lava flow-resurfacing.

Babcock is centered at 4.13 degrees north latitude, 94.14 degrees east longitude, according to the International Astronomical Union’s (IAU) Gazetteer of Planetary Nomenclature. The northern hemisphere crater’s northernmost and southernmost latitudes reach 5.8 degrees north and 2.65 degrees north, respectively. The eastern hemisphere crater’s easternmost and westernmost longitudes extend to 95.71 degrees east and 92.56 degrees east, respectively. Babcock Crater’s diameter spans 95.28 kilometers.

Zasyadko is small, bowl-shaped lunar impact crater that presents proximitous placement to the crater’s midpoint. Zasyadko’s interior floor is relatively small.

Zasyadko is centered at 3.96 degrees north latitude, 94.19 degrees east longitude. It confines its northernmost and southernmost latitudes to 4.12 degrees north and 3.79 degrees north, respectively. It restricts its easternmost and westernmost longitudes to 94.36 degrees east and 94.02 degrees east, respectively. Zasyadko Crater has a diameter of 10.27 kilometers.

Babcock Crater parents two satellites. Both Babcock H and Babcock K associate with their parent’s eastern side.

Babcock H resides along its parent’s eastern side. Satellite H lies to the northeast of Babcock K. Babcock H’s placement qualifies it as the most easterly and most northerly of the Babcock Crater system’s two satellites.

Babcock H is centered at 3.11 degrees north latitude, 96.51 degrees east longitude. It finds its northernmost and southernmost latitudes at 4.15 degrees north and 2.06 degrees north, respectively. It posts easternmost and westernmost longitudes of 97.55 degrees east and 95.46 degrees east, respectively. Babcock H’s diameter of 63.4 kilometers qualifies it as the larger of the Babcock Crater system’s two satellites.

Babcock K resides to the east-southeast of its parent. Satellite K’s placement qualifies it as the more distant and the more southerly of the Babcock Crater system’s two satellites.

Babcock K is centered at 1.19 degrees north latitude, 95.14 degrees east longitude. Its northernmost and southernmost latitudes narrow to 1.35 degrees north and 1.02 degrees north, respectively. It marks its easternmost and westernmost longitudes at 95.31 degrees east and 94.98 degrees east, respectively. Babcock K’s diameter of 9.98 kilometers qualifies it as the smaller of the Babcock Crater system’s two satellites.

The Babcock Crater system resides on far side’s northeastern edge of Mare Smythii (Smyth’s Sea), just beyond the near side’s northeastern limb. The equatorial lunar mare (Latin: mare, “sea”) wraps around the moon’s leading (eastern near side) limb in its occupancy of the near side’s and far side’s portions of the moon’s northern, southern and eastern hemispheres.

Mare Smythii is centered at minus 1.71 degrees south latitude, 87.05 degrees east longitude. The equatorial lunar mare’s northernmost and southernmost latitudes stretch to 4.5 degrees north and minus 7.46 degrees south, respectively. Its easternmost and westernmost longitudes touch 92.72 degrees east and 80.94 degrees east, respectively. Mare Smythii’s diameter spans 373.97 kilometers.

Babcock Crater honors American astronomer Harold Delos Babcock (Jan. 24, 1882-April 8, 1968). The International Astronomical Union (IAU) approved Babcock as the crater’s official name in 1970, during the organization’s XIVth (14th) General Assembly, which was held in Brighton, United Kingdom, from Tuesday, Aug. 18, to Thursday, Aug. 27. Prior to its official naming, Babcock Crater was referenced as Crater 189.

The letter designations for the Babcock Crater system’s two satellites received approval in 2006. Prior to its official naming, Babcock H was identified as Crater 192.

Harold Delos Babcock’s interests in astronomy especially concerned solar spectroscopy and solar magnetism. Babcock pursued his interests via the Carnegie Institution of Washington’s Mount Wilson Observatory (MWO) in Los Angeles County’s San Gabriel Mountains. His employment at Mount Wilson, at the invitation of American solar astronomer George Ellery Hale (June 29, 1868-Feb. 21, 1938), began on Feb. 1, 1909, according to American astronomer and physicist Ira Sprague Bowen’s (Dec. 21, 1898-Feb. 6, 1973) biography in the National Academy of Sciences Biographical Memoir, published in 1974.

Babcock selected chromium and vanadium, two elements with prominent lines in the solar spectrum, for his investigations of the Zeeman effect of magnetic field-caused splitting of spectral lines into components. In 1911, Babcock published his findings on the Zeeman effect for chromium and for vanadium in the April 1911 and October 1911 issues, respectively, of the Astrophysical Journal.

After his Feb. 1, 1948, official retirement from Mount Wilson Observatory, Babcock and his son, Horace Welcome Babcock (Sept. 13, 1912-ug. 29, 2003), collaborated on measuring the sun’s magnetic field. The father-son team published their findings in the December 1952 issue of Publications of the Astronomical Society of the Pacific.

The takeaways for Babcock Crater, which honors American astronomer Harold Delos Babcock, are that the lunar impact crater lies along the northeastern Mare Smythii (Smyth’s Sea) on the lunar far side, just beyond the near side’s northeastern limb; that Babcock Crater parents two satellites; and that the crater’s namesake made significant contributions to solar magnetism and solar spectroscopy.

Detail of Shaded Relief and Color-Coded Topography Map shows Babcock Crater’s equatorial-latitude occupancy of the northeastern edge of Mare Smythii (Smyth’s Sea): U.S. Geological Survey, Public Domain, via USGS Astrogeology Science Center / Gazetteer of Planetary Nomenclature

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Details of Lunar Astronautical Chart (LAC) 64 shows the lunar far side’s Babcock Crater with its two satellites on the northeastern edge of Mare Smythii (Smyth’s Sea); courtesy NASA (National Aeronautics and Space Administration) / GSFC (Goddard Space Flight Center) / ASU (Arizona State University): Public Domain, via USGS Astrogeology Science Center / Gazetteer of Planetary Nomenclature @ https://planetarynames.wr.usgs.gov/images/Lunar/lac_64_wac.pdf

Detail of Shaded Relief and Color-Coded Topography Map shows Babcock Crater’s equatorial-latitude occupancy of the northeastern edge of Mare Smythii (Smyth’s Sea): U.S. Geological Survey, Public Domain, via USGS Astrogeology Science Center / Gazetteer of Planetary Nomenclature @ https://planetarynames.wr.usgs.gov/images/moon_farside.pdf

For further information:

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