Tuesday, October 13, 2015

Moon: Menelaus

Lunar Orbiter 4 image. "Menelaus crater 4090 h2" by James Stuby based on NASA image
Licensed under Public Domain via Commons
Menelaus Crater
Menelaus is a young lunar impact crater located on the southern shore of Mare Serenitatis near the eastern end of the Montes Hæmus mountain range. To the southwest is the small crater Auwers, and to the southwest is the even smaller Daubrée. To the northeast is a faint rille system named the Rimae Menelaus.

The wall of Menelaus is slightly irregular in outline, with a high, sharp rim and terraced inner walls. The interior has a high albedo that is prominent under high sun angles. There are several ridges on the floor. It also has a moderate ray system, with the most prominent ray aligned to the north-northeast across the Mare Serenitatis. The location of this ray and slightly off-center central peak suggest an impact at a relatively low angle.

Menelaus of Alexandria
Menelaus of Alexandria (Greek: Μενέλαος, Menelaos; c. 70 – 140 AD) was a Greek mathematician and astronomer, the first to recognize geodesics on a curved surface as natural analogs of straight lines.

Ptolemy (2nd century AD) also mentions, in his work Almagest (VII.3), two astronomical observations made by Menelaus in Rome in January of the year 98. These were occultations of the stars Spica and Beta Scorpii by the moon, a few nights apart. Ptolemy used these observations to confirm precession of the equinoxes, a phenomenon that had been discovered by Hipparchus in the 2nd century BC.

Sphaerica is the only book that has survived, in an Arabic translation. Composed of three books, it deals with the geometry of the sphere and its application in astronomical measurements and calculations.

Excerpts from Wiki texts have been incorporated into the blog as kinds of abstracts for reader's convenience. By clicking the links much more can be learned about these subjects.

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