Wurzelbauer and the giant “cowpat”

Wurzbauer_Harry Roberts

As indicated on the previous post, the moon is the easiest celestial body to observe and a wealth of detail can be seen even through a small telescope. Here is another of the exquisite lunar drawings by amateur astronomer and member of the Sydney City Skywatchers Harry Roberts:

This is the story Roald Dahl didn’t write!

Amongst the vast crater fields of the lunar southern highlands are many marvellous formations, but none are stranger than WurzelbauerWurzelbauer is a big crater at 88 km diameter. And in the middle of it is a huge mass of ….what is it?

Wurzelbauer is a very ancient crater like most of the highland craters, about 4.5 billion years old, and probably resulted during the accretion process that formed the Moon itself. The sketch shows a normal crater wall on the west side; but on the east side the rim is unusually soft and degraded, and rolls smoothly into crater Gauricus. The east rim has suffered some big hits with secondary craters B, Z and N.

In the middle of Wurzelbauer is a strange mass of “weathered” lunar rock that seems to be raised well above the crater floor itself. The mass is about 40 km across. On Earth such a twisted mass would have been shaped by wind and water; but these do not act on the Moon. Wood tells us (in “Modern Moon – A Personal View” page 133) that “Kuiper thought that its floor was disturbed by incipient melting, and there is indeed a smooth patch with a rille on the floor’s eastern quadrant.” He goes on to ask “Is this mass of rugged material ejected from the Humorum basin impact”?

Johann P. von Wurzelbauer, 1651 – 1725, was a German solar astronomer whose name was applied to the crater by Schröter in 1802. Take a close look at this unique lunar crater, and see if you can interpret the strange central formation.

Enjoy moon watching.

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