The week of March 30 – April 5 takes us from Day 12 to Day 18. This week we will highlight the moon craters Hercules & Atlas, visible on Saturday night close to the terminator.
Hercules and Atlas: [NE/E13-14; L=39°E] Just east of Lacus Mortis (the “Lake of Death”) are two splendid moon craters, Hercules and Atlas. They have been described variously as “noble, magnificent, spectacular, scarcely surpassed.” Although in Greek mythology Hercules and Atlas were contemporaries, the moon craters named after them appeared at widely different times. You should be able to tell at a glance which crater is older.
There is a large simple moon crater on the floor of Hercules. Can you tell if it is bowl-shaped or does it have a flat floor? Atlas has central peaks, rilles, a hummocky floor, and two small dark haloes known as lunar pyroclastic deposits. It is also one of the Moon’s many examples of a floor-fractured crater (FFC). Hercules has multiple terraces, and if you look very closely at it under the right lighting, you will notice two small bumps that are reminiscent of the moon crater Cassini, which you will encounter on Day 7 [E10]. These tiny bumps, located just north of the large internal moon crater Hercules G, are actually the tops of enormous mountains that have been almost entirely inundated by abundant lava flows. Hercules is also the site of reported lunar transient phenomena (LTP’s). Did you notice that both Atlas and Hercules have blankets of surrounding ejecta, known as a glacis?
OF ADDITIONAL INTEREST IN SPACE
On Friday, Mercury is at greatest elongation west of the Sun.
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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
- Aristoteles Adjoins the Moon Crater Mitchell - April 6, 2026
- East of Lacus Mortis on the Moon: Hercules and Atlas - March 30, 2026
- Aristoteles – Complex Moon Crater with Terraces - March 23, 2026