Serenitatis is roughly circular and sits between Mare Imbrium<\/a> to the west and Mare Tranquillitatis<\/a> to the southeast. Less well defined to the southwest is Mare Vaporum.<\/p>\n For more lunar observing advice, read our guides on how to observe the Moon<\/a> and the best features on the Moon<\/a>.<\/strong><\/em><\/p>\n To the northeast Serenitatis overspills into an irregular region north of 96km Posidonius<\/span>, a crater that appears to have an inner floor tilted up in the east.<\/p>\n South of Posidonius is the dark, circular but broken form of 61km Le Monnier<\/span>, resembling a less impressive version of the 400km x 260km Sinus Iridum, the \u2018Bay of Rainbows\u2019, located on the northwest shore of 1,250km Mare Imbrium<\/span>.<\/p>\n Le Monnier is a crater infilled with lava from Mare Serenitatis.<\/p>\n South of Le Monnier lies a complex area around 31km Littrow<\/span>, which consists of elevated highlands interspersed with flat, lowland lava.<\/p>\n The 30km Taurus-Littrow Valley<\/span> is in the region south of Littrow, marking the location of the last human presence on the Moon, the Apollo 17 landing site.<\/p>\n Continuing south brings us to the border between Mare Serenitatis and Mare Tranquillitatis.<\/p>\n A strong contrast between the darker lava of Tranquillitatis and the lighter material of Serenitatis is very apparent here, with the latter being the younger of the two lunar maria<\/a>.<\/p>\n The craters Dawes<\/span> (18km) and Plinius <\/span>(43km) are all that sit in the 200km-wide region where Serenitatis meets Tranquillitatis.<\/span><\/p>\n The western end of the gap is terminated by a pointed feature known as Promontorium Archerusia<\/span>, arcing toward 27km crater Menelaus<\/span>.<\/p>\n Running across Serenitatis\u2019s surface, north-northeast through 17km Bessel<\/span>, is a bright ejecta ray from 86km Tycho Crater<\/span><\/a>, located 2,000km south-southwest.<\/p>\n If we continue northwest around Serenitatis\u2019s border we come to 12km <\/span>Sulpicius Gallus<\/span>, a crater marking the start of an impressive set of rilles, or narrow channels, expanding like the branches of a tree northwest.<\/span><\/p>\n![\""Mare\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2021\/08\/mare-serenitatis-moon-47be432.jpg?quality=90&resize=620%2C469"\" "\\"\"Mare\\"")
<\/div>Facts about Mare Serenitatis<\/span><\/strong><\/h1>\n
![\""Mare\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2019\/02\/moon_4-03450b5.jpg?quality=90&resize=620%2C930"\" "\\"\"Moon_Posidonius_001\"\\"")
<\/div>![\""A\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2019\/02\/LUA1JPG-a39c7ce.jpg?quality=90&resize=620%2C302"\" "\\"\"Moon_Posidonius_003\"\\"")
<\/div>![\""Posidonius\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2019\/02\/lua-3-c11-C-NOME-POSIDONIUS-25mb-5444a77.jpg?quality=90&resize=620%2C449"\" "\\"\"Moon_Posidonius_002\"\\"")
<\/div>![\""Tycho\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2021\/01\/02.SteveFox_TychoCrater-9b27980.jpg?quality=90&resize=620%2C456"\" "\\"\"Tycho\\"")
<\/div>
![\""The\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2019\/02\/appenine-2-NW-05638d3.jpg?quality=90&resize=620%2C435"\" "\\"\"Moon_Apennines_010\"\\"")
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