Earth

Article

August 13, 2022

Earth is the third planet from the Sun in the Solar System, the only planet on which life is known, the home of humanity. Earth belongs to the terrestrial planets and is the largest of these planets in the solar system. The earth is sometimes called the world, the Latin name Terra or the Greek name Gaia. The Earth is the object of research of a significant number of Earth sciences. The study of the Earth as a celestial body belongs to the field of astronomy, the structure and composition of the Earth is studied by geology, the state of the atmosphere by meteorology, and the set of manifestations of life on the planet by biology. Geography provides a description of the features of the topography of the planet's surface — oceans, seas, lakes and rivers, continents and islands, mountains and valleys, as well as human settlements and social formations: cities and villages, states, economic districts, etc.

Planetary characteristics

The Earth revolves around the Sun in an elliptical orbit (very close to circular) with an average speed of 29,785 m/s at an average distance of 149.6 million km with a period approximately equal to 365.24 days (a sidereal year). The Earth has a satellite, the Moon, which orbits the Earth at an average distance of 384,400 km. The inclination of the Earth's axis to the plane of the ecliptic is 66°33′22″. The period of rotation of the Earth around its axis is 23 h 56 min 4.1 s. Rotation around its own axis causes the change of day and night, and the inclination of the Earth's axis to the plane of the ecliptic together with rotation around the Sun causes the change of seasons. The shape of the Earth is a geoid. The average radius of the Earth is 6371.032 km, the equatorial radius is 6378.16 km, and the polar radius is 6356.777 km. The surface area of ​​the globe is 510 million km², the volume is 1.083·1012 km³, the average density is 5518 kg/m³. The mass of the Earth is 5976·1021 kg. The Earth has a magnetic field and a closely related electric field[source?]. The Earth's gravitational field determines its near-spherical shape and the existence of an atmosphere. According to modern cosmogonic ideas, the Earth was formed approximately 4.7 billion years ago from gaseous and dusty matter dispersed in the protosolar system. As a result of the differentiation of the Earth's substance, under the action of the gravitational field, under the conditions of heating of the Earth's interior, the geospheres, which differ in chemical composition, aggregate state, and physical properties of the shell, arose and developed: core, mantle, crust, hydrosphere, atmosphere, magnetosphere. The composition of the Earth is dominated by iron (34.6%), oxygen (29.5%), silicon (15.2%),