Moon, Terebellum III, and Theophilus

Moon, Terebellum III, and Theophilus

November 9th, 2021, 5:26 p.m. local time

The string of consecutive pleasant-weather days and nights continued, though this late afternoon was tempting the streak.  I decided to go for a walk about an hour before taking the pictures in this article, and there were ominous clouds swirling in the South, even though the rest of the sky was clear.  I walked South on a path, and as it twisted and I got better views of the Moon, I saw how those dark clouds were bobbing to and fro, but never getting within the Moon’s vicinity.  I assumed, though, that by the time I reached home, the Soutwest sky would be muddled to the point that any telescopic attempt would be futile.

Thankfully, this worst-case scenario was nowhere to be found, at least in the late afternoon.  Those swirling South clouds stayed mostly near the horizon, giving me ample time to move my Dobsonian to the back deck, allowing the primary mirror to accelemate to the outside temperature, before focusing on the Moon itself.

I leveraged the same focal photography setup from the afternoon before, with the best result shown at the top of this article.  As happened yesterday, I easily noticed another star in the Moon’s vicinity, and captured it here with an overexposed photograph from NightCap:

The Moon with star Terebellum III.

And as before, I checked the exact date and time of my photograph with Stellarium to find out which star this was.  Terebellum III sits on the outskirts of Sagittarius.  At maginitude 4.8, it is likely at the edge of visibility for my area, though I did not wait for a dark enough sky to confirm this.  The star was not visible to me beyond the telescope at the time of photographing.

The Moon and Terebellum III as shown in Stellarium.

This Waxing Crescent is considered a “Day 5” Moon.  I found rather striking the large crater at the shadow’s edge, about a third of the way from the bottom in the top image.  The crater is Theophilus, with a diameter of approximately 100 kilometers.  It is apprxoimately 1 to 3 billion years old.  None of the manned lunar missions landed near it, though Apollo 16 flew over it and landed the closest in 1972.

Closeup of my Moon image to highlight the crater Theophilus.

I know little about lunar colony proposals, but Theophilus seems like it would make for a good future human settlement.  It of course faces the Earth, and is a large surfance formation that can be seen from Earth.  A 60-mile diameter means that it would have more than sufficient area for a nascent colony.  The 1400-meter rising center would provide a unique structural navigation bearing for the residents.  The indenture into the lunar surface may provide some as-yet unknown safety benefits as well.

Would placing lunar colonies inside large craters be a good idea?  Or would flatter, more even surface be better?

Telescope and photography settings for the solo Moon photograph:

  • 254mm Dobsonian (homemade)
  • 1/250 sec exposure
  • ISO 50
  • Q70 32mm eyepiece (2.00″)
  • iPhone XS with NightCap app on eyepiece mount
  • Touchups in PaintShop Pro and AfterShot Pro


I write frequently about astrophotography, technology advice, and my other interests like science fiction. I have over 30 years of experience in computer programming, information technology, and project management.

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