Last Quarter Saturday, Oct. 10, Shows Apollo 12’s Oceanus Procellarum

Summary: The moon’s last quarter Saturday, Oct. 10, shows Apollo 12’s Oceanus Procellarum as an irregularly shaped vast darkness on the lunar trailing side.

Lunar Reconnaissance Orbiter image, released July 9, 2013, shows Apollo 12 and Surveyor 3 landing sites on Surveyor Crater in the Mare Cognitum (Sea That Has Become Known) portion of the lunar near side’s vast Oceanus Procellarum (Sea of Storms); image credit NASA Goddard/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 moon’s last quarter Saturday, Oct. 10, shows Apollo 12’s Oceanus Procellarum as an irregularly shaped darkness vastly stretching across the near side of the moon’s western hemisphere.

October’s last quarter phase begins Saturday, Oct. 10, at 00:39 Greenwich Mean Time/Coordinated Universal Time (Friday, Oct. 9, at 8:39 p.m. Eastern Daylight Time), according to retired NASA astrophysicist Fred Espenak’s AstroPixels website. As the fourth of the moon’s four primary phases, October’s last quarter occurs eight days after the onset of the bright, third primary phase’s full moon on Thursday, Oct. 1, at 21:05 GMT/UTC (5:05 p.m. EDT) and precedes by six days the dark, first primary phase’s new moon of Friday, Oct. 16, which starts at 19:31 GMT/UTC (3:31 p.m. EDT).

Illumination during October’s last quarter phase claims 50 percent (0.50) of the near side’s surface, according to the U.S. Naval Observatory’s Astronomical Applications Department website. The last quarter and its counterpart phase, the first quarter, are also known as half moons for their coverage of opposite halves of the moon’s near side.

At 50 percent lunar surface visibility, the last quarter moon Saturday, Oct. 10, shows Apollo 12’s Oceanus Procellarum as a dominating darkness that sweeps along a significant portion of the western limb. Oceanus Procellarum is centered at 20.67 degrees north latitude and minus 56.68 degrees west longitude, according to the International Astronomical Union’s (IAU) Gazetteer of Planetary Nomenclature. Its northernmost and southernmost latitudes reach to 57.43 degrees north and minus 16.27 degrees south, respectively. As a western hemisphere lava plain, its easternmost and westernmost longitudes extend to minus 26.85 degrees west and minus 81.08 degrees west, respectively. Oceanus Procellarum spans a diameter of 2,592.24 kilometers.

The National Aeronautics and Space Administration’s (NASA) Apollo 12 mission safely landed Commander Charles “Pete” Conrad Jr. (June 2, 1930-July 8, 1999) and Lunar Module Pilot Alan LaVern Bean (March 15, 1932-May 26, 2018) as the second pair of moonwalking astronauts. Apollo Lunar Module Intrepid settled Wednesday, Nov. 19, 1969, at 06:54:35 Universal Time (1:54:35 a.m. Eastern Standard Time), in southeastern Oceanus Procellarum.

Belgian astronomer and cartographer Michael Florent van Langren (April 27, 1598-May 1675) identified the moon’s largest so-called sea as Oceanus Philippicus, in honor of his patron, King Philip IV of Spain (April 8, 1605-Sept. 17, 1665), in his 1645 map, Plenilunii Lumina Austriaca Philippica, the first known map of the moon. In 1651, Italian Jesuit astronomers Francesco Maria Grimaldi (April 2, 1618-Dec. 28, 1663) and Giovanni Battista Riccioli (April 17, 1598-June 25, 1671) renamed the dark expanse as Oceanus Procellarum (Ocean of Storms) in their two-volume, encyclopedic reference work on astronomy, Almagestum Novum (New Almagest).

The Intrepid landed on the northwestern rim of Surveyor Crater, which sits in the Mare Cognitum (Sea That Has Become Known) portion of Oceanus Procellarum. Northern Hemisphere moonwatchers know Mare Cognitum as the right side of the lunar near side’s Man in the Moon.

Intrepid’s touchdown point lies only 530 feet (163) from the target point, the crater’s namesake, the Surveyor 3 spacecraft, according to human spaceflight historian Ben Evan’s Nov. 12, 2014, post, 45 Years Since Apollo 12, on AmericaSpace website. The NASA Surveyor program’s third robotic spacecraft soft-landed on the crater’s eastern inner slope on Thursday, April 20, 1967, at 00:04:53 UT (Wednesday, April 19, at 8:04 p.m. EDT).

Surveyor Crater has a diameter of 0.2 kilometers. The southwestern hemisphere crater's center coordinates are minus 3.01 degrees south latitude, minus 23.42 degrees west longitude.

The takeaway for the last quarter’s Oct. 10 showing of Apollo 12’s Oceanus Procellarum is that the third and fourth humans to walk on the moon landed in southeastern Oceanus Procellarum’s Mare Cognitum, the dark lava plain that represents the right side of the Man in the Moon’s mouth for Northern Hemisphere moonwatchers.

Of six Apollo lunar landing sites, only Apollo 16’s touchdown in the south central lunar Descartes Highlands misses participation in or proximity to any of the lunar dark patches that form the features of the Man in the Moon for Earth’s Northern Hemisphere moonwatchers; Apollo 12’s landing site in the Mare Cognitum portion of the near side’s Oceanus Procellarum falls within the right side of the Man in the Moon’s mouth: NASA/Goddard Space Flight Center Scientific Visualization Studio, via NASA

Acknowledgment

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

Image credits:

Lunar Reconnaissance Orbiter image, released July 9, 2013, shows Apollo 12 and Surveyor 3 landing sites on Surveyor Crater in the Mare Cognitum (Sea That Has Become Known) portion of the lunar near side’s vast Oceanus Procellarum (Sea of Storms); image credit NASA Goddard/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 @ https://www.nasa.gov/content/lunar-reconnaissance-orbiter-looks-at-apollo-12-surveyor-3-landing-sites

Of six Apollo lunar landing sites, only Apollo 16’s touchdown in the south central lunar Descartes Highlands misses participation in or proximity to any of the lunar dark patches that form the features of the Man in the Moon for Earth’s Northern Hemisphere moonwatchers; Apollo 12’s landing site in the Mare Cognitum portion of the near side’s Oceanus Procellarum falls within the right side of the Man in the Moon’s mouth: NASA/Goddard Space Flight Center Scientific Visualization Studio, via NASA Science Earth’s Moon @ https://moon.nasa.gov/resources/52/apollo-landing-sites/ and via NASA @ https://www.nasa.gov/mission_pages/LRO/multimedia/lroimages/lroc_20090903_apollo12.html

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