The week of September 18-24 takes us from Day 28 (essentially new moon) to Day 4. The Moon won’t be in a good position for viewing until around Saturday (the end of Day 3). This week we will highlight the crater Gutenberg, visible on Sunday night.
Gutenberg: [SE/K14] On Sunday night you can drop down below the Sea of Fertility and pay your respects to one of history’s great men. Gutenberg crater is not only of historical importance because of its namesake, it shows an unusual sequence of crater development. Gutenberg is a large crater (45 mi. in diameter) that is intruded upon by a smaller crater (12 mi. in diameter–Gutenberg E) on its eastern wall. So far so good. But take a close look at the crater immediately adjoining it to the south (Gutenberg C). These craters have violated the usually dependable rule that newer craters are smaller than the older craters they have intruded upon. Gutenberg C is the older crater, while the larger Gutenberg is the interloper.
Another item of interest is the simple crater on the southwest rim (Gutenberg A). Simple craters start with rounded floors then progress to a flat floor resulting from a cascade of boulders that have rolled down the interior walls and settled at the bottom. Rim shadows on bowl-shaped floors will appear as a smooth arc. The floor is flat because it has been partially filled in.
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]
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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