April 2017 Waxing Gibbous Moon Shows Mare Nectaris in Lunar Southeast

Summary: The April 2017 waxing gibbous moon, which phases between the first quarter and full moon, shows Mare Nectaris in the lunar southeast quadrant.

Mare Nectaris in lunar southeast: USGS Astrogeology Science Center, Public Domain, Wikimedia Commons

The April 2017 waxing gibbous moon, which phases between Monday, April 3’s first quarter moon  and Tuesday, April 11’s full moon, shows Mare Nectaris in the lunar southeast quadrant.

Mare Nectaris, which translates as Sea of Nectar, occupies the near side of the moon. The small volcanic lava plain lies south of two much larger lava plains. Mare Tranquillitatis (“Sea of Tranquility”) is to the north, and Mare Fecunditatis (“Sea of Fecundity”) lies to the northeast.

The nearly circular volcanic lava plain has a diameter 339.39 kilometers (210.88 miles). As one of the smallest of the moon’s features known singularly as mare and plurally as maria, Mare Nectaris has a surface area of 100,000 square kilometers (38,610.216 square miles).

The easy visibility afforded by Mare Nectaris to naked astronomy encourages further exploration of the small lava plain and its neighbors via binocular, naked eye and telescopic astronomy. A variety of landforms define the southeastern mare’s edges.

Sinus Asperitatis (“Bay of Roughness”) bridges Mare Tranquillitatis’ southern extent and Sea of Nectar’s northwestern edge. The ridged and wrinkled lava plain has a diameter of 219.14 kilometers (136.167 miles).

Conjoined lunar impact craters Cyrillus and Theophilus also hug the northwestern edge. The prominent pair of older Cyrillus and younger Theophilus actually form a linked trio with ancient Catharina, whose heavily eroded northern section connects with Cyrillus’ southern wall. Largest of the trio, Catharina has a diameter of 98.77 kilometers (61.37 miles).

The three comparably-sized craters, named by Jesuit astronomer Giovanni Battista Riccioli (April 17, 1598-June 25, 1671), commemorate three saints of Alexandria, Egypt. Catharina’s namesake, Saint Catherine of Alexandria, was beheaded as a Christian teen-aged martyr, ca. 305, by order of Roman Emperor Maxentius (ca. 278-Oct. 28, 312). Cyrillus honors Egyptian theologian Saint Cyril, 24th Coptic Pope of Alexandria (death in 444). Theophilus memorializes Saint Cyril’s uncle, Saint Theophilus, 23rd Coptic Pope of Alexandria (died Oct. 15, 412).

Theophilus juts dramatically into the terrain where Sinus Asperitatis fuses with Mare Nectaris. Theophilus has a diameter of 98.59 kilometers (61.26 miles). Theophilus’ southwestern rim is a partial intruder into Cyrillus’s northeastern rim.

Cyrillus has a diameter of 98.09 kilometers (60.95 miles). Its jumbled floor and walls contrast with Theophilus’ wide floor and broadly terraced inner walls.

South-southeast of Theophilus, Beaumont perches on Mare Nectaris’ western edges. Beaumont has a diameter of 50.69 kilometers (31.497 miles). Lava flows from Mare Nectaris flooded the crater’s interior by breaching its eastern rim. The breach, described by amateur astronomer Peter Grego (1965-2016) as less than 10 kilometers (6.2 miles) in width, does not interfere with Beaumont’s overall shape. Beaumont recalls French geologist Jean-Baptiste Armand Louis Léonce Élie de Beaumont (Sept. 25, 1798-Sept. 21, 1874).

Southeast of Beaumont, Fracastorius is settled as a giant semicircle along the southwestern shore of Mare Nectaris. Its diameter measures 120.58 kilometers (74.92 miles). The ancient, lava-flooded lunar impact crater has lost much of its northern wall to erosion from Mare Nectaris’ lava flows. Consequently, Fracastorius appears as a bay-like extension. Fracastorius’ namesake is Italian astronomer and physician Girolamo Fracastoro (ca. 1476/1478-Aug. 6, 1553).

The Montes Pyrenaeus (“Pyrenees Mountains”) range claims Mare Nectaris’ eastern border. Montes Pyrenaeus stretches from north to south for 251.33 kilometers (156.169 miles). The lunar mountain range, named by German astronomer Johann Heinrich von Mädler (May 29, 1794-March 14, 1874), honors the Pyrenees Mountains that range as a natural border between France and Spain in southwestern Europe.

Continued observations of Mare Nectaris lead to identification of features on the small lava plain's floor as well as of more surrounding landforms. Mare Nectaris' neighborhood may also be observed during other lunar phases, such as the first quarter and full moon in the Northern Hemisphere. In the Southern Hemisphere, where opposite portions are illuminated, phases offering visibility of Mare Nectaris include full, waning gibbous and third quarter.

The takeaway for the April 2017 waxing gibbous moon phase’s setting for Mare Nectaris in the lunar southeast is the volcanic lava plain’s easy, naked eye visibility, which encourages deepening familiarity via binocular, naked eye and/or telescopic explorations.

lunar near side’s major craters and maria; full moon originally imaged with Celestron 9.25 Schmidt-Cassegrain telescope Friday, Oct. 22, 2010, 23:21, from Madison, north central Alabama: Peter Freiman (Cmglee), Gregory H. Revera (background photography), 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:

Mare Nectaris in lunar southeast: USGS Astrogeology Science Center, Public Domain, Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:FracastoriusCraterLOC.jpg?uselang=fr

lunar near side’s major craters and maria; full moon originally imaged with Celestron 9.25 Schmidt-Cassegrain telescope Friday, Oct. 22, 2010, 23:21, from Madison, north central Alabama: Peter Freiman (Cmglee), Gregory H. Revera (background photography), CC BY SA 3.0 Unported, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Moon_names.svg

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