Humans formed belief systems based on stellar bodies. If you ask an astrologer about it, he might tell you his beliefs which of those have the most influence on your life. If you ask a scientist, he will likely name at least two: Sun and Earth. Ancient cultures already measured a phenomenon that - relative to each other - Earth rotates around the sun as well as around its own axis. A full rotation around itself is called a "day", a full rotation around the sun a "year". Relatively speaking, that is in relation to the sun, Earth returns to its current position after one year. One hundred such rotations are called a "century". A man who is on Earth for such a time is called a "centennial". A centennial who contributes to endgame theory is called... Yuri Averbakh. | Photo of Averbakh: Eteri Kublashvili