In the episode What Is Pi? we learned how to draw a circle arts-and-crafts style. To do this, start by cutting a 3-inch piece of string to serve as the radius of the circle.

However, I recently wanted to draw a circle for my post on the distance to the horizon, and decided to ask an expert: The Little Astronomer, who showed me how to do it in about 20 seconds.

THERE’S no getting around it - drawing a perfect freehand circle without even looking is a seriously impressive skill. And it’s been captured in this astonishing how-to video. Man begins to ...