November 22, 2014

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What Did Galileo See?

left image from Galileo; right image by Peter Rosén, Stockholm, Sweden

Last month, I photographed the first quarter of the Moon with a 400 mm lens and Albategnius appeared as the hub of the lunar disc. Magnifying the image made it less obvious because of the multitude of smaler craters that started to compete. Albategnius has often been sugested to be the oversize crater drawn by Galileo and published in "Sidereus Nuncius" in March 1610. How come that Galileo, being such a skilled observer, represented this crater almost 3 times bigger and so much offset from it's correct position? The question of the size can possibly be somewhat explained by the visual impact that this crater makes on the observer. And Galileo must have had difficulties in observing, for his telescope had a very narrow field of view so he could only see a tiny part of the Moon at a time, and the view had many optical flaws. It must also have been a constant and difficult task to recenter the Moon as it drifted out of the field of view. Taking all these factors into account, it must have been a most difficult task to draw the whole surface and at the same time get the correct proportions and positions. Another anomaly is that Galileo has drawn Mare Serenitatis on the terminator of the first quarter and I think he mixed it up with Mare Imbrium. Or did he make a final drawing from sketches taken over several days?

In 2009, I had the chance to see one of Galileos telescopes that was on display at the Nobel museum in Stockholm to commemorate the 400th anniversary of it's invention.
I was deeply moved at the view of this modest tube with flawed optics that started such a scientific revolution and understanding of our universe… and we are still a part of this same revolution.

Peter Rosén

Technical Details
Right image: 30 October 2014 at 18h03 UT with a Canon Eos5D and a 70-200 zoom with a 2x teleconverter.

Related Links
As we approach the end of LPOD I like it that this image and text nearly match the very first LPOD (and that the original LPOD slash screen specifically linked the earliest study of the Moon with the latest).

Still remember 51 years ago today, when the man who sent us to the Moon died.

Yesterday's LPOD: The Quadruplet

Tomorrow's LPOD: The Joy of Seeing


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