Geminus and Bernoulli

2010 08 26, 0737 UT Geminus and Bernoulli
PCW Memorial Observatory, OH, USA, Erika Rix –
Zhumell 16”, 12mm Burgess, 2x Barlow, 300x mag, 13% T moon filter
Temp: 15.1C, > 90% humidity, S: Antoniadi III-I
Sketch created scopeside with Rite in the Rain paper and charcoal.

Phase: 342.4°
Lunation: 16.19d
Illumination: 97.6%
Lib. Lat: -5°48’
Lib. Long: -2°06’
Az: 206°48’, Alt: 46°49’

*Geminus:* complex crater, 56.7° E, 34.5°N
Eratosthenian Period (-3.2 billion yrs to –1.1 billion yrs)
Dimension: ~88×52 km, Height: 5400 km
Named after Geminus of Rhodes. Depending on which reference you use, he
was said to have lived in 70 BC or in 50 AD (or thereabouts) and was a
mathematician and astronomer.

Although this is a circular formation, it appears oblong because of an
effect called foreshortening caused by its position near the limb. Even
the central ridge appears offset from the midpoint of the crater floor.
The moon filter helped bring out more details not only in the terraced
walls of the crater but also the extensive ejecta and formations
surrounding Geminus. An area of interest is northern rim of the crater.
In the sketch, there are two bright circular areas representing notches
that I first believed were craters. The rim itself appeared well-defined
and very sharp.

Geminus C (16×16 km) is located just southeast of Geminus and Messala A
(26×26 km) is located a little further to the northwest.

*Bernoulli: *crater, 60.7° E, 45° N
Upper Imbrian period (-3.8 billion yrs to –3.2 billion yrs)
Dimension: ~49×49 km, Height: 4000 km
Named after Jacques Bernoulli, 17th century Swiss mathematician and

The central mountain in this crater was visible just outside of the
encroaching shadow. The terraced southern rim appears to spill into the
outer surroundings and the northern edge seemed to plateau connecting
like a bridge to Bernoulli A.

The full report can be found here:
2010 08 26, Geminus and Bernoulli

Erika Rix

5 thoughts on “Geminus and Bernoulli”

  1. Erika,

    Beautiful sketch, excellent labeling and interesting written observation as well as the research information you add. I really enjoy your work!

  2. Absolutely marvelous!

    Great detail, for me really difficult with charcoal.

    Brava Erika!


  3. An incredibly realistic rendering. It appears to be the result of a great and talented effort. A unique style that is most compelling. Very impressive.

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