From: David Grosof To: jeevacation <jeevacation@gmail.com> Subject: Video showing the fractal geometry of lunar surface and tricky shape from shading cues Date: Mon, 14 Jan 2019 20:17:55 +0000 Hi, Jeffrey, I think you will enjoy checking out this video of the Chinese spacecraft landing on the far side of the moon. https://www.syfy.corn/syfywire/amazing-video-chinese-lander-and-rover-descend-to-the-moons-far-side (1) Determining the altitude/distance to the surface is hard/impossible until the very end when dust kicks up. It's a great illustration of self-similarity across a lot of spatial scale in a geological surface, and implicitly of how the absence of atmospheric blurring/softening of detail contributes to the difficulty of distance determination. (2) Craters sometimes turn into bumps/hillocks because of the way the brain sorts out shape from shading info. Illustrations in this article (click through) are "prompts": https://www.scientificamerican.com/article/seeing-isbelieving-aug-08/ Enjoy! d. EFTA01008525