ABSTRACT
This chapter reviews the evolution of scientific thinking about the processes that have shaped the earth’s surface. The sun is surrounded by bodies of various types that follow elliptical orbits as they revolve around the sun. The sun occupies one of the foci of the orbits. The trajectories of the planets lie very close to the same plane. The Earth takes 365.256 days to revolve around the sun, which necessitates one leap year every four years. The length of the year has probably not changed significantly during the history of the Earth. The astronomy of the solar system is now well understood, but the same is not true of the nature of the bodies that circle the sun. The only planets that have dense atmospheres today are Earth and Venus. The Earth’s atmosphere is predominantly nitrogen and oxygen. Venus’s atmosphere is essentially carbon dioxide with a total pressure 96 times higher than that of Earth.
