This lesson provides an overview of solar and lunar calendars, their history and lore and also, of the day and the month, and their relations to the rotation period of the Earth and the orbital period of the Moon. Students learn the differences between a solar day, sidereal day and mean solar day, and what each is used for as well as the differences between the solar year and the Julian and Gregorian calendars. Students will also become familiar with the Moon cycle (synodic period), the orbital period of the Moon, and the reason they differ, the Metonic and Moslem calendars, and some facts about the calendar of the Mayan culture, which thrived in Mesoamerica before Columbus.