IAO 1998, Теория, 14–16 години — Задача 1

The Moon has a synodic period (i.e. period of rotation relative to the Sun) of 29.53 days. Therefore the Sun is visible from any place of the lunar surface during periods of about 2 weeks. Between these periods it will be under the horizon for about 2 weeks. As for the Earth, the situation is different: the Earth is always visible from the side of the Moon that can be seen from the Earth, but from the other side it is never seen. It means that one can see the Earth more often from the visible side of the Moon, and only the Sun from the other side.