For thousands of years, people have seen patterns in the stars in the night sky. Groups composed mainly of stars form recognizable patterns called constellations. Early people recognized that they could tell the basic seasons by looking at certain constellation within a zone called the ecliptic. The ecliptic is a band in the sky defined by the trace of the Sun on June 21 (highest in the sky) and December 20 (lowest in the sky). Constellations recognized in this zone are referred to as the Zodiac. This was an important mark to ancient people who were mainly farmers. It was a celestial calendar that helped them determine when to plant their crops and to get ready for winter.

Many civilizations used monuments to help them recognize the onset of time. Stonehenge, an ancient ruin in England is probably some type of solar and celestial calendar to mark these heavenly events.

Stonehenge in England