October’s Blue Moon Saturday, Oct. 31, Shows Apollo 15’s Mare Imbrium

Summary: October’s blue moon Saturday, Oct. 31, shows Apollo 15’s Mare Imbrium as the Man in the Moon’s large right eye for Northern Hemisphere moonwatchers.

artist’s concept of Apollo 15’s Hadley-Apennine landing site shows planned traverses in Lunar Roving Vehicle (LRV); Roman numerals for extravehicular activities (EVAs) and Arabic numbers for traverse station stops; illustration by NASA graphic artist Jerry Elmore; artist's concept excerpted from "On the Moon with Apollo 15: A Guidebook to Hadley Rille and the Apennine Mountains" (June 1971; figure 3, page 8) by Gene Simmons, Manned Spacecraft Center Chief Scientist: NASA ID S71-33433 (July 1, 1971): 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 Image and Video Library

October’s blue moon Saturday, Oct. 31, shows Apollo 15’s Mare Imbrium as a large, round, dark, basaltic lava plain representing the Man in the Moon’s right eye for Northern Hemisphere moonwatchers.

October’s second full moon begins on Halloween, Saturday, Oct. 31, at 14:49 Greenwich Mean Time/Coordinated Universal Time (10:49 a.m. Eastern Daylight Time), according to retired NASA astrophysicist Fred Espenak’s AstroPixels website. The second of two full moons within the same month is known as a blue moon.

The National Aeronautics and Space Administration’s (NASA) Apollo 15 mission safely landed Commander David Randolph Scott (born June 6, 1932) and Lunar Module Pilot James “Jim” Benson Irwin (March 17, 1930-Aug. 8, 1991) as the seventh and eighth persons to walk on the moon. Apollo Lunar Module Falcon touched down Friday, July 30, 1971, at 22:16:29 Universal Time (6:16 p.m. EDT) on the eastern margin of Mare Imbrium.

Mare Imbrium occupies the northwestern quadrant of the moon’s near side. It is centered at 34.72 degrees north latitude, minus 14.91 degrees west longitude, according to the International Astronomical Union’s (IAU) Gazetteer of Planetary Nomenclature. The mare’s large darkness claims northernmost and southernmost latitudes of 51.46 degrees and 15.23 degrees, respectively. Its easternmost and westernmost longitudes stretch to 8.56 degrees and minus 38.36 degrees, respectively.

Mare Imbrium’s diameter measures 1,145.53 kilometers. Its great diameter qualifies Mare Imbrium for second place in size among the moon’s maria (Latin: mare, “sea”; plural: maria). Oceanus Procellarum (Ocean of Storms) sprawls along the lunar near side’s western hemisphere as the largest lunar mare. Its diameter spans 2,592.24 kilometers. Eastern Oceanus Procellarum’s adjacency to southwestern Mare Imbrium allows the moon’s two largest maria to dominate the near side’s western hemisphere.

Mare Imbrium (Sea of Showers) owes its name to the Italian Jesuit astronomers Francesco Maria Grimaldi (april 2, 1618-Dec. 28, 1663) and Giovanni Battista Riccioli (April 17, 1598-June 25, 1671). The name appears on a lunar map in their two-volume, encyclopedic reference work on astronomy, Almagestum Novum (New Almagest), published in 1651.

Lunar Module Falcon settled on Palus Putredinis (Marsh of Decay). The nearly level, dark, lava-flooded plain is located on Mare Imbrium’s southeastern extremity. The plain is centered at 27.36 degrees north latitude, 0 degrees longitude. Its northernmost and southernmost latitudes reach 29.4 degrees and 25.31 degrees, respectively. The plain’s easternmost and westernmost longitudes extend to 2.85 degrees and minus 2.77 degrees, respectively. Palus Putredinis has a diameter of 180.45 kilometers. Grimaldi and Riccioli are credited with naming Palus Putredinis in Almagestum Novum.

The Universities Space Research Association’s (USRA) Lunar and Planetary Institute (LPI) describes Falcon’s landing site as a “mare-filled embayment in the Apennine Mountains.” The site’s topographic landmarks include the Apennine Mountains’ Mons Hadley Delta to the south and Hadley Rille to the west.

The rugged Montes Apenninus range marks Mare Imbrium’s southeastern border. The range is centered at 19.87 degrees north latitude, 0.03 degrees east longitude. The range’s northernmost and southernmost latitudes stretch from 28.47 degrees to 14.63 degrees, respectively. Easternmost and westernmost longitudes for Montes Apenninus reach 7.34 degrees and minus 10.21 degrees, respectively. In 1961, the IAU approved naming the range after the Apennines, or Apennine Mountains (Italian: Appennini), that stretch across the length of peninsular Italy.

Mons Hadley Delta (δ) is centered in the northern Montes Apenninus at 25.72 degrees north latitude, 3.71 degrees east longitude. The massif’s northernmost and southernmost latitudes reach 25.99 degrees and 25.44 degrees, respectively. Easternmost and westernmost longitudes are recorded at 3.86 degrees and 3.46 degrees, respectively. The massif’s diameter measures 17.24 kilometers. Mons Hadley Delta rises to approximately 3,500 meters (11,500 feet) above the landing site, according to Lunar and Planetary Institute (LPI) staff scientist Julie Stopar in her June 20, 2014, post on NASA ASU (Arizona State University) Lunar Reconnaissance Orbiter Camera (LROC) website.

Rima Hadley is described by the Lunar and Planetary Institute as “the sinuous channel that winds along the western margin of the Apennine Mountains.” Hadley Rille (German: rille, “groove”) is centered at 25.72 degrees north latitude, 3.15 degrees east longitude. The rille’s northernmost and southernmost latitudes extend to 26.7 degrees and 24.53 degrees, respectively. Easternmost and westernmost longitudes register at 3.58 degrees and 2.26 degrees, respectively.

The namesake for Mons Hadley Delta and Rima Hadley is English mathematician John Hadley (April 16, 1682-Feb. 14, 1744). Hadley became an IAU-approved name in 1935.

The takeaway for October’s blue moon Saturday, Oct. 31, is that the month’s second full moon shows Apollo 15’s Mare Imbrium as the Man in the Moon’s large right eye for Northern Hemisphere moonwatchers.

NASA’s Lunar Reconnaissance Orbiter Camera’s (LROC) image of Apollo 15 landing site in the lunar near side’s Hadley-Apennine region shows traverse plots of the first two of the mission’s three extravehicular activities (EVAs); north is to the right; elevations above the landing site, indicated by LM (lunar module), given in meters; distance from LM to Elbow Crater approximates 4.5 kilometers (2.8 miles); LM is sited 2 kilometers from sinuous Hadley Rille; LROC NAC M1123519889: NASA/GSFC/Arizona State University via NASA

Acknowledgment

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

Image credits:

artist’s concept of Apollo 15’s Hadley-Apennine landing site shows planned traverses in Lunar Roving Vehicle (LRV); Roman numerals for extravehicular activities (EVAs) and Arabic numbers for traverse station stops; illustration by NASA graphic artist Jerry Elmore; artist's concept excerpted from "On the Moon with Apollo 15: A Guidebook to Hadley Rille and the Apennine Mountains" (June 1971; figure 3, page 8) by Gene Simmons, Manned Spacecraft Center Chief Scientist: NASA ID S71-33433 (July 1, 1971): 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 Image and Video Library @ https://images.nasa.gov/details/S71-33433

NASA’s Lunar Reconnaissance Orbiter Camera’s (LROC) image of Apollo 15 landing site in the lunar near side’s Hadley-Apennine region shows traverse plots of the first two of the mission’s three extravehicular activities (EVAs); north is to the right; elevations above the landing site, indicated by LM (lunar module), given in meters; distance from LM to Elbow Crater approximates 4.5 kilometers (2.8 miles); LM is sited 2 kilometers from sinuous Hadley Rille; LROC NAC M1123519889: NASA/GSFC/Arizona State University via NASA @ https://www.nasa.gov/content/goddard/apollo-15-original-interplanetary-mountaineers; via NASA ASU LROC @ http://www.lroc.asu.edu/posts/783

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