November 29, 2013

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New Crater Formed?

image by Aerts Leo, Belgium

Leo has been observing the Moon for a long time, originally drawing what he saw, and in recent years acquiring digital images. Here is a comparison of the two techniques, with an accomplished drawing of Albategnius from 1979 and an excellent image with opposite lighting from this year. Leo comments, I made many such drawings. It was fun and as an observer one gained experience in recording minute details on the lunar surface, that were out of reach of the films of that time. Drawing is an excellent way to improve observing skills. This drawing has remarkable detail, as if the outline had been traced from a photo and the details added at the telescope. In comparing the drawing and image there are various subtle differences in the details, but look not even too closely and you'll notice a major difference. Near the bottom of the Albategnius image there is a large oval crater nearly completely in shadow, with a smaller but distinct one to it's upper right and another to the left. These do not appear on the 1979 drawing. In the 1800s such a change would be interpreted as evidence for the formation of new features, but earlier photos show they existed, so the likely explanation here is that the artist concentrated on other details - such as the shape and details of the rim - so much that other parts of the scene were only cursorily examined. This reinforces the idea that drawings, no matter how evocative or beautiful, are an interpretation and can not be relied on for historical accuracy.

Chuck Wood

Related Links
21st Century Atlas chart 12.

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