Today, we have lots of tools1 at our disposal to examine the topography of our nearest neighbor, but measurements of lunar mountains were being recorded long before the development of satellites, space travel, and photography.  How was it done? With a keen understanding of light and shadow and a whole lot2 of geometry. The earliest […]

Phases of the Moon – Hevelius, Selenographia, p. 182:

Last week, while looking for the largest/clearest/awesomest version of the Moon map that I posted, I got totally sucked into the book in which it appears, the 1647 Selenographia of Johannes Hevelius.  While the image quality of the scanned book isn’t great, I thought I’d share a few of my favorite figures anyway.  Since I study craters […]

This map of the near side of the Moon was published in Johannes Hevelius’ 1647 book Selenographia. You might notice that it covers slightly more than one hemisphere.  Hevelius recognized that the Moon librates (in both longitude and latitude) as it orbits the Earth, letting us peek at an extra 9% of its surface. I love the […]