Fossils provide the evidence that life has evolved interactively with Earth through geologic time. Evolution is a theory that explains how life has changed through time. All material in the universe, including living organisms, appears to be composed of the same elements and to behave according to the same physical principles. All bodies in space, including Earth, are influenced by forces acting throughout the Solar System and the universe. Nine planets, including Earth, revolve around the sun in nearly circular orbits.
Earth is a small planet, third from the Sun in the only system of planets definitely known to exist.
The position and motions of Earth with respect to the Sun and Moon determine seasons, climates, and tidal changes. The rotation of Earth on its axis determines day and night. Teachers, scientists, and technicians who study Earth are employed by businesses, industries, government agencies, public and private institutions, and as independent contractors. Careers in the sciences that study Earth may include sample and data collection in the field and analyses and experiments in the laboratory. Scientists from many cultures throughout the world cooperate and collaborate using oral, written, and electronic means of communication.