Image Courtesy of Earth Day Energy Fast
Earth is the third planet from the sun and the largest of the terrestrial planets. Earth is the first planet to have water and the only known planet to harbor life in the universe. Earth has a magnetic field and an atmosphere primarily made up of nitrogen and oxygen that protects the surface from radiation that is harmful to life. This shield will also burn up smaller meteorites that enter it.
The Earth was formed approximately 4.57 billion years ago. Its only natural satellite, the Moon, began its orbit around 4.53 billion years ago, which can change the ocean’s tides. At the present the Earth orbits the Sun once every 366.26 days. The Earth’s axis is tilted toward the Sun causing seasonal shifts.
About 71% of the Earth’s surface is made up of salt water oceans. The remaining 29% of this is made up of islands and continents. The outer surface of the Earth is made up of tectonic plates. The interior of the planet is made up of a thick layer of relatively solid mantle, a liquid outer core that generates a magnetic field, and a solid iron core.