The earth formed about 4.54 billion years ago, and life has appeared on the surface at least about 3.5 billion years ago. The Earth's biosphere then slowly changes the atmosphere and other basic physical conditions, which enable the proliferation of organisms and the formation of the ozone layer, which together with the Earth's magnetic field blocks harmful solar radiation and allows microscopic living things to multiply safely on land. Physical properties, geological history, and Earth's orbit allows life to continue to survive.
The lithosphere of the Earth is divided into several rigid segments, or tectonic plates, which experience movement across the entire surface of the Earth for millions of years. More than 70% of the surface of the Earth is covered by water, and the rest consists of continents and islands with many lakes and other sources of water contributing to the formation of the hydrosphere. The Earth's poles are mostly covered in ice, solid ice in the Antarctic ice sheet and sea ice in the polar ice pack. The interior of the Earth is still active, with the inner core consisting of solid iron, while the outer core in the form of a fluid that creates a magnetic field, and a thick layer that is relatively dense in the mantle.
The earth interacts gravitationally with other objects in space, especially the Sun and the Moon. When circling the Sun in one orbit, the Earth rotates on its axis 366.26 times, which creates 365.26 solar days or a sidewalk year. The rotation of the Earth on its axis is tilted 23.4° from across the orbital plane, which causes a difference in the seasons on the Earth's surface with a tropical one year period (365.24 sun days). The moon is the only natural Earth satellite, which begins to orbit the Earth around 4.53 billion years ago. The gravitational interaction between the Moon and Earth stimulates sea tides, stabilizes the tilt of the axis, and gradually slows the rotation of the Earth.
The earth is home to millions of living things, including humans. Earth's mineral resources and other biosphere products contribute to providing resources to support the global human population. The territory inhabited by humans is grouped into 200 sovereign countries, which interact with each other through diplomacy, travel, trade and military action.
In modern English, the noun earth was developed from the Middle English word erthe (recorded in 1137), which comes from the Old English word eorthe (before 725), while the word itself comes from the Proto-Germanic word erthō. Earth has relatives in all other Germanic languages, including aarde in Dutch, Erde in German, Jordan Swedish, Danish and Norwegian. Earth is a parable for the Germanic pagan goddess (or Jörð in Norse mythology, mother of the gods Thor).
In Indonesian, the word earth comes from Sanskrit Bhumi, which means land, and is always written in capital letters ("Earth"), to refer to planet Earth, while "earth" with lowercase letters refers to the surface of the world, or land.
Heat in the Earth comes from a combination of heat deposits from planetary accretion (about 20%) and heat produced by radioactive decay (80%). The main isotope producing the Earth is potassium-40, uranium-238, uranium-235, and thorium-232. At the center of the Earth, temperatures can reach 6,000°C, and the pressure reaches 360 GPa. Because much of the Earth's heat is produced by radioactive decay, scientists believe that at the beginning of Earth's history, before short-lived isotopes are drained, the production of geothermal energy produced is much higher compared to today. The heat produced at that time is estimated to be twice as large as it is today, about 3 billion years ago, and this will increase the temperature gradient inside the Earth, increase the level of mantle convection and plate tectonics, and allow rock formation frozen like the komatiites, which cannot be formed today.