It was named after the Athenian philosopher and mathematician, Proclus Diadochus (410-485 AD).<\/span><\/p>\n Proclus lies at the eastern tip of the Palus Somni, the Marsh of Sleep.<\/span><\/p>\n It has a very sharp rim, and the walls are steep and continuous. There is a low central mountain, which I always find a very easy object to observe with a small telescope.<\/span><\/p>\n For more info on lunar observing, read our guides on how to observe the Moon<\/a> and the best features on the Moon<\/a>.<\/strong><\/em><\/p>\n Proclus crater is the centre of a bright ray system, but unlike the major ray systems this one is not symmetrical.<\/span><\/p>\n To the east lies an upland, on the far side of which is the famous Mare Crisium<\/a>, the Sea of Crises.<\/span><\/p>\n The rays extend across the uplands and on to the Mare Crisium, and they are fairly prominent when seen under high illumination.<\/span><\/p>\n The situation to the west of Proclus is quite different. The rays extend for some distance but do not enter the Palus Somnii.<\/span><\/p>\n Instead, the marsh is bounded to either side by a ray, and the colour of the darker material towards the rays is rather unusual.<\/span><\/p>\n It is clear that the Proclus rays were formed in a different manner from those of the major systems such as Tycho crater<\/a>. <\/span><\/p>\n On the side of the Mare Crisium facing Proclus there are two capes \u2013 Lavinium and Olivium.<\/span><\/p>\n The capes are separated by two low, curved ridges, and many years ago some observers reported seeing a \u2018bridge\u2019 from one cape to the other. This is certainly not the case \u2013 there is nothing at all strange about these two capes.<\/span><\/p>\n The land towards the Mare Crisium and Proclus is brighter, and very rough, with no particularly well-marked formations. <\/span><\/p>\n There is one crater, Fredholm, which is 13km across and fairly regular in shape. I have looked for a central mountain inside it, but I have never seen one.<\/span><\/p>\n The position of Proclus means that it comes into view not very long after a new Moon, and remains visible until well after the full Moon<\/a>, before it is cut off from the sunlight.<\/span><\/p>\n![\""Small\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2021\/08\/Proclus-crater-90e6e51.jpg?quality=90&resize=620%2C487"\" "\\"\"Small\\"")
<\/div>Facts about Proclus crater<\/strong><\/h1>\n
![\""Crater\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2019\/02\/PROCLUS-S-b6a6dfe.jpg?quality=90&resize=620%2C320"\" "\\"\"Moon_Proculus_001\"\\"")
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![\""Diagram\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/25\/2021\/08\/Mare-Crisium-eebdf44.jpg?quality=90&resize=620%2C430"\" "\\"\"The\\"")
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