Today I don’t have anything big. I just wanted to point people to “Spherical Cycloids”, a post on the WordPress blog The Inner Frame. Cycloids are somewhat familiar, at least to kids who grew up in the United States in my age cohort, because you get them out of spirographs. You make them by taking some point within a rotatable object. Roll that object along the path, normally one that’s defined by another shape. You can get wonderful and strange and exotic-looking curves, many with a hypnotic regularity.
The Inner Frame made a variation of this. It’s got cycloids drawn on the surface of the sphere. This immediately adds a new level of strangeness and wonder to the curves. The pictures are lovely and hypnotic. Folks with 3-D printers can probably also make some grand exotic candleholders from the pattern, too.