Moon: Day 8 - “Hints of Timocharus”
Published on 28 Apr 2004 at 6:29 am.
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One more clear midnight hour here and very mild - a hint of things to come. The Moon is now 8 days and 16 hours old and located in the middle of the dim constellation Cancer. So, a -10 magnitude Moon washes away +4 magnitude stars well! At 75x, the lunar terminator is found at 12 degrees west longitude - to the west edge of the deep crater Eratosthenes. This is an black “inkwell” at the end of the mighty Apennines mountain range. These mountains make up part of a rough ring about Mare Imbrium even through the 10x finderscope. North of it, crater Plato (63 mi.) is roughly 1/2 sunlit within - roughly because the zigzag shadow of its eastern rim is cast onto its floor! Just to the south of Plato, the Mons Pico casts it long shadow westward to the terminator; the tops of the Teneriffe Mountains gleam of sunlight barely beyond this day-night line. Have any of you noticed the difference of the shadow length cast by Mons Piton now and yesterday morning? To the south, crater Tycho is barely into view, but as a round “inkwell.” The rays leading to it so well during a near full Moon are not well seen to it now. The crater thus is much more anonymous so far. The elevated east rim of large Clavius adds to the terminator with its shadow, but Maginus to the northeast of it has its floor almost all illuminated. How many of you have taken notice of the bright “V” within this crater open wide as the Sun angle lessens? The same can be said of Deslandres, but it’s interior small crater of Hell is black within, to appropriately correspond with its name. Already, the subtle crater of Hipparchus has “melted” back into the lunar surface with more direct sunlight, but small Alpetragius (40 km) is almost completely shaded within, being some 3900 meters deep! If there is any time to see the Rupes Recta in Mare Nubium at its best, it is now, as it appears as a distinct, thin straight black line. The furthest south crater of significance recognized is Moretus (73 mi.) at 70 deg. south latitude. It has a shaded interior now, but its central peak barely catches sunlight on top. “inkwell” crater Gruemberger (93.6 km) is juxtaposed northwest of it, as if competing for the oncoming sunlight. Although with cloudiness forecast here tomorrow morning, most of Mare Nubium should be revealed by the lunar terminator then, and the eye-catching craters with large size and stark relief to be seen best will be Copernicus and Clavius. Take out the binoculars and telescope and enjoy!