The week of December 22-28 takes us from Day 3 to Day 9. This week we will highlight the moon crater Clavius, visible on Sunday night close to the terminator.
Clavius: [SW/Q8; L=14°W] If you catch the Moon at the end of Day 7 or early in Day 8 when the terminator is around 15° (i.e., it cuts right through Clavius), and if you have determined that you can see objects that are as small as 2 arc-minutes with the naked eye, look at the Moon without benefit of telescope or binoculars and you might be able to see a small notch that has been chiseled out of the terminator in the southern portion of the Moon. This notch is the moon crater Clavius. If you need to, double-check with binoculars then go back and see if you can detect it with your naked eyes. Come back tomorrow night to see Clavius in its full glory.
Sunrise over Clavius is something that you don’t want to miss! The moon crater is so large (140 miles) that the curvature of the Moon pushes the floor’s central regions into the sunlight first. As the day progresses, the shadows will retreat to reveal a floor that is strewn with craterlets. There is a delightful arc of small craters, artistically and sequentially arranged in order of size, which begins at Rutherfurd, a 34-mile crater just inside the southeast rim, arcs northward and then diminishes toward the west. While the Sun angle is low over Clavius, look for several ridges that extend like fingers northward from Rutherfurd. The origin of these ridges remains a mystery. Revisit Clavius often. You will always see something that you missed previously.
OF ADDITIONAL INTEREST IN SPACE
The Ursid meteor shower peaked on Monday.
On Friday, Saturn is 4° south of the Moon.
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It is highly recommended that you get a copy of Sky and Telescope’s Field Map of the Moon, the very finest Moon map available for use at the telescope. It is available for $10.95 at www.skyandtelescope.com and on Amazon. All features mentioned in this blog will be keyed to the grid on the Field Map and will look like this: Plato: [NW/D9]
Credits:
Courtesy of Gray Photography of Corpus Christi, Texas
Lunar photos: NASA / USGS / BMDO / LROC / ASU / DLR / LOLA / Moon Globe. Used by permission
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