Earth and Space News: Apollo 11 landing site southwestern Mare Tranquillitatis

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Wednesday, September 30, 2020

First October 2020 Full Moon Shows Apollo 11’s Mare Tranquillitatis

Summary: The first October 2020 full moon shows Apollo 11’s Mare Tranquillitatis on Oct. 1, as the Man in the Moon’s left eye for Northern Hemisphere viewers.

NASA’s Lunar Reconnaissance Orbiter Camera (LROC) image Sept. 29, 2009, shows the Apollo 11 landing site (Eagle Descent Stage), along with Laser Ranging Retro-Reflector (LRRR) and Passive Seismic Experiment (PSE), west of Little West and West craters, on the flats of southwestern Mare Tranquillitatis; image credit NASA/Goddard Space Flight Center/Arizona State University: Generally not subject to copyright in the United States; may use this material for educational or informational purposes, including photo collections, textbooks, public exhibits, computer graphical simulations and Internet Web pages; general permission extends to personal Web pages, via NASA

The first October 2020 full moon shows Apollo 11’s Mare Tranquilitatis on Thursday, Oct. 1, as the irregularly shaped, dark lava plain that Northern Hemisphere viewers identify as the Man in the Moon’s left eye.

The first of two full moons shining in October 2020 takes place Thursday, Oct. 1, at 21:05 Greenwich Mean Time/Coordinated Universal Time (5:05 p.m. Eastern Daylight Time), according to retired NASA astrophysicist Fred Espenak’s AstroPixels website. The month’s second full moon, known as a blue moon, happens Oct. 31, at 09:49 GMT/UTC (5:49 p.m. EDT).

At 100 percent lunar surface visibility, the full moon Thursday, Oct. 1, shows Apollo 11’s Mare Tranquillitatis as the middle of three dark, roughly circular shapes that slant downward below Mare Crisium (Sea of Crises). The oval, wringled-edged lava plain perches by itself near the moon’s leading limb. Mare Crisium is centered at 16.18 degrees north latitude, 59.1 degrees east longitude. Its diameter measures 555.92 kilometers.

The National Aeronautics and Space Administration’s (NASA) Apollo 11 mission safely landed American astronauts Neil Alden Armstrong (Aug. 5, 1930-Aug. 25, 2012) and Edwin “Buzz” Eugene Aldrin Jr. (born Jan. 20, 1930) as the first two people on Earth’s moon. The Apollo Lunar Module Eagle made the first manned landing July 20, 1969, at 20:17 UTC (4:17 p.m. EDT), in southwestern Mare Tranquillitatis.

Mare Tranquillitatis is an irregularly shaped, basaltic lava plain in the near side of the moon’s northeastern quadrant. Planetographic coordinates for Mare Tranquillitatis identify the lava plain’s center latitude at 8.35 degrees north and its center longitude at 30.83 degrees east, according to the International Astronomical Union’s (IAU) Gazetteer of Planetary Nomenclature. Its northernmost and southernmost latitudes reach to 19.37 degrees north and minus 4.05 degrees south, respectively. As an eastern hemisphere lava plain, its easternmost and westernmost longitudes extend to 45.49 degrees east and 16.92 degrees east, respectively.

With a diameter of 875.75 kilometers (544.16 miles), Mare Tranquillitatis lies in the Tranquillitatis Basin. The basin’s formation likely traces to a very large impact in the moon’s early prehistory, probably dating back more than 3.9 billion years, according to the Lunar Reconnaissance Orbiter mission pages on NASA’s website. Tranquillitatis Basin is centered on 0.68 degrees north latitude, 23.43 degrees south longitude. The basin’s northernmost and southernmost latitudes roughly extend from 20.4 degrees north to minus 4.4 degrees south. Its easternmost and westernmost longitudes roughly stretch from 45.9 degrees east to 15.0 degrees east.

Italian Jesuit astronomers Francesco Maria Grimaldi (April 2, 1618-Dec. 28, 1663) and Giovanni Battista Riccioli (April 17, 1598-June 25, 1671) are credited with naming Mare Tranquillitatis in 1651. The name appeared in a lunar map in their two-volume, encyclopedic reference work on astronomy, Almagestum Novum (New Almagest).

Mare Tranquillitatis translates as Sea of Tranquility, in American English. British English doubles the letter l for spelling as Sea of Tranquillity.

The Eagle landed approximately 400 meters (1,312 feet) west of West Crater, according to the Smithsonian’s National Air and Space Museum website. The sharp-rimmed, rayed crater is centered at 0.67 degrees north latitude, 23.49 degrees east longitude. West Crater’s diameter measures 0.19 kilometers.

The Apollo 11 landing site is proximitous to Little West Crater, according to NASA Goddard Space Flight Center and Arizona State University’s Lunar Reconnaissance Orbiter Camera (LROC) website. Little West Crater lies approximately 50 meters (164 feet) east of the landing site. The Gazetteer of Planetary Nomenclature gives center coordinates of 0.67 degrees north latitude and 23.48 degrees east longitude for Little West. The small crater’s diameter measures 0.04 kilometers.

At 20:17:58 UTC, approximately 18 seconds after the Eagle’s successful landing, Commander Armstrong referred to the landing site as Tranquility Base. In 1970, the International Astronomical Union, which serves as the international authority for planetary and satellite names, approved Statio Tranquillitatis (Tranquility Base) as the site’s official name. IAU naming conventions require that the dark patches, mistakenly perceived as seas by early astronomers, have names in Latin that describe weather and abstract concepts.

Statio Tranquillitatis has a center latitude of 0.67 degrees north. Its center longitude is 23.47 degrees east.

The takeaway for the first October 2020’s showing of Apollo 11’s Mare Tranquillitatis is that the first two humans to walk on the moon landed in southwestern Mare Tranquillitatis, the dark lava plain that represents the Man in the Moon’s left eye for Northern Hemisphere moonwatchers.

Apollo 11’s Mare Tranquillitatis (Sea of Tranquility) landing site lies in the lava plain’s southwestern flats; Mare Crisium (Sea of Crises) perches near the moon’s leading limb, above the southeasterly slanting trio of Mare Serenitatis (Sea of Serenity), Mare Tranquillitatis and Mare Fecunditatis (Sea of Fecundity); Friday, Oct. 22, 2010, 23:21, image of full moon photographed from Madison, north central Alabama, with Canon EOS Rebel T1i (EOS 500D) digital camera on Celestron 9.25 Schmidt-Cassegrain telescope: Soerfm, CC BY SA 3.0 Unported, via Wikimedia Commons

Acknowledgment

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

Image credits:

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Dunbar, Brian; and Lynn Jenner, ed. “Mare Tranquillitatis.” NASA > Missions > LRO (Lunar Reconnaissance Orbiter) > Multimedia. Last updated June 4, 2010.
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Espenak, Fred. “Phases of the Moon: 2001 to 2020 Greenwich Mean Time (GMT).” AstroPixels > Ephemeris > Moon > Phases of the Moon From 2001 to 2100.
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International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN). “Little West.” USGS Astrogeology Science Center > Gazetteer of Planetary Nomenclature. Last updated July 26, 2017.
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International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN). “Statio Tranquillitatis.” USGS Astrogeology Science Center > Gazetteer of Planetary Nomenclature. Last updated Oct. 25, 2010.
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Available via LROC (Lunar Reconnaissance Orbiter Camera) ASU (Arizona State Univerity) SESE (School of Earth and Space Exploration) @ http://lroc.sese.asu.edu/posts/484
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Wednesday, April 4, 2012

Menzel Crater Honors American Theoretical Astrophysicist Donald Menzel

Summary: Menzel Crater honors American theoretical astrophysicist Donald Menzel, total solar eclipse observer and Harvard College Observatory’s sixth director.

Detail of Lunar Astronautical Chart (LAC) 61 shows Menzel Crater (center left) as a near side crater, with nearest named neighbor Maskelyne F, in southeastern Mare Tranquillitatis; courtesy NASA (National Aeronautics and Space Administration) / GSFC (Goddard Space Flight Center) / ASU (Arizona State University): U.S. Geological Survey, Public Domain, via USGS Astrogeology Science Center / Gazetteer of Planetary Nomenclature

Menzel Crater honors American theoretical astrophysicist Donald Menzel, who served as Harvard College Observatory’s (HCO) sixth director and, over 55 years, between 1918 and 1973, observed 15 total solar eclipses.

Menzel Crater is a lunar impact crater in the near side’s northeastern quadrant. The tiny crater is circular and cup-shaped.

Menzel Crater is centered at 3.41 degrees north latitude, 36.94 degrees east longitude, according to the International Astronomical Union’s (IAU) Gazetteer of Planetary Nomenclature. The northern hemisphere crater obtains northernmost and southernmost latitudes of 3.46 degrees north and 3.35 degrees north, respectively. Its easternmost and westernmost longitudes occur at 37 degrees east and 36.89 degrees east, respectively. Menzel Crater’s diameter measures 3.44 kilometers.

Menzel lies in southeastern Mare Tranquillitatis (Sea of Tranquility). The lunar mare is famously associated with the first crewed lunar landing, achieved by the National Aeronautics and Space Administration’s (NASA) Apollo 11 spaceflight on Sunday, July 20, 1969.

Mare Tranquillitatis is centered at 8.35 degrees north latitude, 30.83 degrees east longitude. It records northernmost and southernmost latitudes of 19.37 degrees north and minus 4.05 degrees south, respectively. The Sea of Tranquility registers easternmost and westernmost longitudes of 45.49 degrees east and 16.92 degrees east, respectively. Mare Tranquillitatis has a diameter of 875.75 kilometers.

Maskelyne F is Menzel Crater’s nearest named neighbor. Maskelyne F lies to the northwest of Menzel Crater.

Maskelyne F numbers among the 16 satellites in the Maskelyne Crater system. The system’s primary crater, Maskelyne, logs a center-to-center distance of 210 kilometers from Apollo 11’s Mare Tranquillitatis landing site, according to the Lunar and Planetary Institute’s webpage on the Apollo 11 Mission’s landing site.

Maskelyne F is centered at 4.18 degrees north latitude, 35.3 degrees east longitude. The satellite posts northernmost and southernmost latitudes of 4.52 degrees north and 3.83 degrees north, respectively. It marks easternmost and westernmost longitudes at 35.64 degrees east and 34.95 degrees east, respectively. Maskelyne F’s diameter spans 20.93 kilometers.

Menzel Crater honors American theoretical astrophysicist Donald Howard Menzel (April 11, 1901-Dec. 14, 1976). The International Astronomical Union (IAU) approved Menzel as the tiny crater’s official name in 1979, during the organization’s XVIIth (17th) General Assembly, held from Tuesday, Aug. 14, to Thursday, Aug. 23, in Montreal, Canada.

Menzel received his Ph.D. in astrophysics from Princeton University in 1924. His advisor, Henry Norris Russell (Oct. 25, 1877-Feb. 18, 1957), was the first practitioner of the new field of astrophysics in the United States, according to American astronomers Leopold “Leo” Goldberg (Jan. 26, 1913-Nov. 1, 1987) and Lawrence Hugh Aller (Sept. 24, 1913-March 16, 2003) in the National Academy of Sciences’ Biographical Memoir, published in 1991. Menzel’s dissertation, “A Study of Line Intensities in Stellar Spectra,” considered a temperature scale for stellar spectra.

In 1952, Menzel was appointed as acting director of Harvard College Observatory (HCO). In January 1954, he became the observatory’s sixth director, a position that he held until 1966. In 1955, Menzel shepherded a beneficial association with the Smithsonian Institution. The transfer of the Smithsonian Astrophysical Observatory (SAO) from Washington DC to Cambridge in 1955 culminated in the establishment of the Harvard-Smithsonian Center for Astrophysics (CfA) in 1973.

Menzel’s interest in solar eclipses traced to his viewing of the total solar eclipse of June 8, 1918, as a Boy Scout over Evergreen, Colorado. Over the next 55 years, he enthusiastically added 14 more total solar eclipses to his solar eclipse portfolio. He traveled to western Mauritania to view the eclipse of June 30, 1973, as his last total solar eclipse.

Menzel’s retirement home in Costa Rica eased his observation of the annular eclipse of Dec. 24, 1973, as his last solar eclipse. Costa Rica qualified as one of the eclipse’s visibility regions.

In addition to his sophisticated astrophysics writings, Menzel published A Field Guide to the Stars and Planets, Including the Moon, Satellites, Comets, and Other Features of the Universe as a popular astronomy best-seller in 1964. The guide helpfully grouped the 88 modern constellations recognized by the International Astronomical Union into eight families as a memory aide for their locations.

The takeaways for Menzel Crater, which honors American theoretical astrophysicist Donald Howard Menzel, are that the tiny crater lies in southeastern Mare Tranquillitatis (Sea of Tranquility) in the near side’s northeastern quadrant; that Menzel is circular and cup-shaped; and that Menzel Crater’s namesake studied at Princeton University with Henry Norris Russell, who pioneered astrophysics in the United States; that Donald Menzel pursued his interest in solar eclipses by observing 15 total solar eclipses over 55 years; and that his publishing output includes a popular astronomy best-seller, A Field Guide to the Stars and Planets (1964), which helpfully groups the modern 88 constellations into eight families.

Detail of Shaded Relief and Color-Coded Topography Map shows Menzel Crater (center), northeast of Apollo 11 landing site (center left), in southeastern Mare Tranquillitatis, in the lunar near side’s northeastern quadrant: 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:

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