Raditladi Quadrangle Is Fourth of 15 Quadrangles of Mercurian Surface

Summary: Raditladi Quadrangle is the fourth of 15 quadrangles of the Mercurian surface and covers northern midlatitudes longitudinally from 180 to 270 degrees.

Raditladi Quadrangle residents Raditladi Crater (upper left), Cunningham, Kertész and Sander craters (upper center) and Apollodorus and Atget craters and Phantheon Fossae (upper right); name-labeled mosaic of Narrow Angle Camera (NAC) images shows 12 features imaged for first time via MESSENGER's first flyby Jan. 14, 2008, and announced April 9, 2008, via USGS Astrogeology Science Center as officially named and three craters (Basho in Michelangelo Quadrangle H-12; Mozart and Tolstoj in Tolstoj Quadrangle H-8) first seen by Mariner 10 mission; credit NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington; uploaded May 2, 2008, by Bryan Derksen, Public Domain, via Wikimedia Commons

Raditladi Quadrangle is the fourth of 15 quadrangles of the Mercurian surface and references the Swift Planet's low and middle latitudes of 21 to 66 degrees north latitude, from 180 to 270 degrees west longitude.

As the fourth of Mercury's 15 quadrangles, Raditladi Quadrangle has the letter-number designation of H-4 or H04. H denotes Hermes, Greek mythology's equivalent of Roman mythology's Mercurius.

Raditladi Quadrangle's provisional name, Liguria, reflects on Italy's northwest region and derives from the ancient, mysterious Ligures people, whose territory once included northwestern Italy, southern France and part of modern Catalonia in northeastern Spain. Greek French astronomer Greek French astronomer Eugène Michel Antoniadi (March 1, 1870-Feb. 10, 1944) centered Liguria at approximately 40 degrees north latitude on the map of Mercury's albedo features in his guide, La Planète Mercure, published in 1934 and translated into English by English amateur astronomer Sir Patrick Moore (March 4, 1923-Dec. 9, 2012) in 1974 (figure 5, page 26).

Mercury's quadrangles conventionally derive their names from prominent features. Raditladi Quadrangle's namesake is Raditladi Crater. The International Astronomical Union (IAU) has established names of historically significant artists, authors, musicians and painters as the theme for Mercury's craters, according to the IAU's U.S.G.S. (U.S. Geological Survey) Astrogeology Science Center-maintained, online Gazetteer of Planetary Nomenclature. Raditladi Crater received IAU approval on April 8, 2008, as the Mercurian namesake of Botswanan playwright and poet Leetile Disang Raditladi (1910-1971).

Raditladi Crater is centered at 27.15 degrees north latitude, 240.94 degrees west longitude, according to the IAU's Gazetteer of Planetary Nomenclature. The northern low latitude crater obtains northernmost and southernmost latitudes of 30.17 degrees north and 24.12 degrees north, respectively. Its easternmost and westernmost longitudes occur at 237.54 degrees west and 244.34 degrees west, respectively. Raditladi Crater's diameter measures 258 kilometers.

In their presentation, "The Curious Case of Raditladi Basin," at the 40th annual Lunar and Planetary Science Conference, held Monday, March 23, to Friday, March 27, 2009, Planetary scientist Louise M. Procktor and 11 co-authors described Raditladi Crater as distinguished structurally by an off-center peak-ring with a diameter of approximately 125 kilometers. Extensional (pulled-apart) troughs that occur as a partially concentric, circularly-patterned complex within the peak-ring structure qualify as a rarity on the Mercurian surface. The distinctive flat floors exhibited in some of the troughs are considered as graben (German: "ditch"), depressed blocks of planetary or satellite crust.

Raditladi Crater lies to the west of Caloris Planitia (Hot Plain). The IAU approved the name of southeastern Raditladi Quadrangle's huge plain in 1976 as one of two exceptions (Borealis Planitia, "Northern Plain") to the convention of assigning names of Mercury, as god or planet, in various languages to the Swift Planets plains (Latin: planitiae). In addition to its Raditladi occupancy, Caloris Planitia extends into Shakespeare Quadrangle to the east and Tolstoj Quadrangle to the south.

Caloris Planitia is centered at 31.65 degrees north latitude, 198.02 degrees west longitude. Its northernmost and southernmost latitudes extend to 48.6 degrees north and 15.54 degrees north, respectively. Its easternmost and westernmost longitudes reach 176.3 degrees west and 217.97 degrees west, respectively. Caloris Planitia's diameter spans 1,500 kilometers.

Raditladi Quadrangle lies to the south of northern polar region's Borealis Quadrangle (H-1). Shakespeare Quadrangle (H-3) and Hokusai Quadrangle (H-5) occur as Raditladi Quadrangle's eastern and western neighbors, respectively. Raditladi Quadrangle shares its southern borders with Tolstoj Quadrangle (H-8) and Eminescu Quadrangle (H-9).

Raditladi Quadrangle numbers among the six Mercurian quadrangles not imaged by the National Aeronautics and Space Administration's (NASA) Mariner 10 mission. The five other quadrangles not covered by Mariner 10 were Raditladi's western neighbor, Hokusai (H-5); Raditladi's southwestern neighbor, Eminescu (H-9); Hokusai's southern neighbor, Derain (H-10); Derain's southeastern neighbor, Debussy (H-14); and Eminescu's southern neighbor, Neruda (H-13). Images obtained from the robotic space probe's three flybys (March 29, 1974; Sept. 21, 1974; March 16, 1975) allowed mapping of nine of the 15 quadrangles that abstractly divide Mercury's surface. MESSENGER robotic space probe's explorations of Mercury removed the mapping gaps via one primary mission, beginning April 4, 2011, and two extensions.

The takeaways for Raditladi Quadrangle as the fourth of 15 quadrangles of the Mercurian surface are that the quadrangle's namesake is Botswanan playwright-honoring Raditladi Crater; that Raditladi Crater exhibits a rare feature, partially-concentric, circularly-patterned troughs thought to be graben, in its off center peak-ring structure; that the quadrangle was identified as Liguria Albedo Province in Greek-French astronomer E.M. Antoniadi's 1934 Mercury guidebook; and that Raditladi Quadrangle shares borders with northern neighbor Borealis Quadrangle, eastern neighbor Shakespeare Quadrangle, southern neighbors Tolstoj and Eminescu quadrangles, and western neighbor Hokusai Quadrangle.

Raditladi Qudrangle's namesake, off-center peak-ringed Raditladi Crater (upper left) was discovered in 3x3 mosaic of three images obtained by the Mercury Dual Imaging System's (MDIS) Wide Angle Camera (WAC) during MESSENGER robotic space probe's first Mercury flyby Jan. 14, 2008; mosaic presents first-ever view of area not covered by NASA's 1974-1975 Mariner 10 mission; credit NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington: Public Domain, 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:

Raditladi Quadrangle residents Raditladi Crater (upper left), Cunningham, Kertész and Sander craters (upper center) and Apollodorus and Atget craters and Phantheon Fossae (upper right); name-labeled mosaic of Narrow Angle Camera (NAC) images shows 12 features imaged for first time via MESSENGER's first flyby Jan. 14, 2008, and announced April 9, 2008, via USGS Astrogeology Science Center as officially named and three craters (Basho in Michelangelo Quadrangle H-12; Mozart and Tolstoj in Tolstoj Quadrangle H-8) first seen by Mariner 10 mission; credit NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington; uploaded May 2, 2008, by Bryan Derksen, Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:MESSENGER%27s_first_view_of_Mercury_with_name_labels.jpg

Raditladi Qudrangle's namesake, off-center peak-ringed Raditladi Crater (upper left) was discovered in 3x3 mosaic of three images obtained by the Mercury Dual Imaging System's (MDIS) Wide Angle Camera (WAC) during MESSENGER robotic space probe's first Mercury flyby Jan. 14, 2008; mosaic presents first-ever view of area not covered by NASA's 1974-1975 Mariner 10 mission; credit NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington: Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Mercury_in_color_-_Prockter07.jpg

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