Document Type : Research Paper

Author

• Abbas Ali Saleh Abadi

Member of Faculty, School of Mapping

Abstract

Since ancient times, human being has endeavored to increase its knowledge of the planet on which it lives, though most of its natural phenomena contain complicated mysteries.
When humans started farming on land, they began to learn about how the length of day and night are reduced or increased, and also about the general changes far from the earth's surface which causes the existence of years.