The week of September 21-27 takes us from Day 11 to Day 17. This week we will highlight the moon crater Clavius, visible on Tuesday 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 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.
OF ADDITIONAL INTEREST IN SPACE
Fall equinox is on Tuesday.
Neptune was discovered on September 23, 1846.
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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
- Petavius: Floor-Fractured Crater on the Moon - October 12, 2026
- Rimae Sirsalis – One of the Longest Rilles on the Moon - October 5, 2026
- Moon Crater Aristoteles Adjoins the Moon Crater Mitchell to its Immediate East - September 28, 2026