Olympiad beginning on the opening of the Olympic Games for the summer sports. The first modern Olympiad began in 1896, the second in 1900, and so on (the 31st began in 2016: see the Olympic Charter). The ancient and modern Olympiads would have synchronised had there been a year zero between the Olympiad of 4 BC and the one of 4 AD. But as the Gregorian calendar goes directly from 1 BC to 1 AD, the ancient Olympic cycle now lags the modern cycle by one year. An ancient Olympiad was a period of four years grouped together, counting inclusively as
International Astronomy Olympiad International Astronomy Olympiad The International Astronomy Olympiad (IAO) is an internationally recognized annual astronomy scientific-educating event for high school students (14–18 years old), which includes an intellectual competition between these students. It is one of the International Science Olympiads. The Eurasian Astronomical Society founded the IAO in 1996. The competing part of IAO consists of three rounds: a theoretical, an observational, and a practical. Problems of the theoretical round involve classical problems in branches of astronomy, astrophysics, space and planetary physics, and maybe hypothetical situations. The observational round involves recognizing stars, constellations, estimating star magnitude and angular distance, working with