More than 2,000 years ago, pretty much every educated human knew the Earth was round. There are some pretty obvious clues, after all. If you travel south, you see stars and constellations you’ve never ...

Mean radius is the average measurement from the true center of the group (white) to the center of each shot. More simply, it's the average "miss distance." Group size, not mean radius, has been the ...

When working with circles it is important to recognise and be able to name different parts of the circle. A segment of a circle is an area enclosed by a chord and an arc. What is the name given to a ...