Background
The crater Ptolemaeus is located close to the center of the nearside of the Moon just south of Sinus Medii. It lies directly south of the crater Herschel. The crater is named after the famous astronomer Claudius Ptolemy. Many books have been written on Ptolemy's contributions to science and he remains one of the most important astronomers in history. He was born in Egypt around 100 A.D. and spent his time in Alexandria. He published the famed "Almagest" which contains a record of ancient historical astronomical models of the sky. He lists 48 constellations which has been converted into our modern system of delineating regions of the sky.
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| Herschel (Image Credit: NASA Apollo 16) |
Ptolemaeus is a fairly large crater with a diameter of 154km and a depth of 2,400m.
Observation
My abbreviated observation record can be found below:
My abbreviated observation record can be found below:
| Date | 2020-05-29 |
| Time | 23:56 |
| Sky | Clear |
| Telescope | 8" Reflector (1200mm F.L.) |
| Eyepiece | 10mm (2x Barlow) |
| Magnification | 240x |
Comments
Ptolemaeus is larger than its neighbouring craters Hipparchus and Albategnius. It appears flooded which would mean it is a fairly old crater. There is a crater on the northeastern quadrant of the floor visible and named Ammonius. The southern edge of the rim is broken by neighbouring Alphonsus.
Location
To help you locate this object a map has been provided from the Royal Astronomical Society of Canada's Observer's Handbook. It is object #75, highlighted below.
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| Ptolemaeus (Crater) |
The image below is a view from the Apollo 12 mission. The Apollo 12 lunar module, Intrepid, can be seen descending to the lunar surface. Ammonius is clearly visible in the foreground with Herschel off the the right of the image.
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| Ptolemaeus (Image Credit: NASA Apollo 12) |
