The word planet has long existed and has a relationship of history, science, mythology, and religion. By ancient civilizations, the planet was seen as something that was immortal or representative of gods. As advances science, man's view of the planet changes.
In 2006, the International Astronomy Association (IAU) passed an official resolution defining planets in the Solar System. This definition is praised but also criticized and is still debated by a number of scientists because it does not include objects with planetary mass that are determined by the place or object of its orbit. Although eight planetary objects discovered before 1950 are still considered "planets" according to modern definitions, a number of celestial bodies such as Ceres, Orcus, Juno, Vesta (each object in the Sun asteroid belt), and Pluto(the first discovered trans-Neptune object) that was once considered a planet by the scientific community is no longer a planet.
The Earth is the third planet from the Sun which is the most populous planet and the fifth largest of the eight planets in the Solar System. 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.