Earth, also known as "the Earth" and "the World", is the third planet from the Sun and the densest planet in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the "Blue Planet",[24] the "Blue Marble", Terra or "Gaia".
According to evidence from sources such as radiometric dating, Earth was formed around four and a half billion years ago. Within its first billion years,[25] life appeared in its oceans and began to affect its atmosphere and surface, promoting the proliferation of aerobic as well as anaerobic organisms and causing the formation of the atmosphere's ozone layer. This layer and Earth's magnetic field block the most life-threatening parts of the Sun's radiation, so life was able to flourish on land as well as in water.[26] Since then, Earth's position in the Solar System, its physical properties and its geological history have allowed life to persist.
Earth's lithosphere is divided into several rigid segments, or tectonic plates, that migrate across the surface over periods of many millions of years. Over 70% percent of Earth's surface is covered with water,[27] with the remainder consisting of continents and islands which together have many lakes and other sources of water that contribute to the hydrosphere. Earth's poles are mostly covered with ice that is the solid ice of the Antarctic ice sheet and the sea ice that is the polar ice packs. The planet's interior remains active, with a solid iron inner core, a liquid outer core that generates the magnetic field, and a thick layer of relatively solid mantle.
Earth gravitationally interacts with other objects in space, especially the Sun and the Moon. During one orbit around the
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formed by the alteration of preexisting rock deep within Earth (but still in the solid state) by heat, pressure, and/or chemically active fluids. * Outer core – A layer beneath the mantle about 2270 km (1410 miles) thick, which has the properties of a liquid. * Sedimentary rock – Rock formed from the weathered products of preexisting rocks that have been transported, deposited, and lithified * Core – The innermost layer of Earth based on composition. It is thought to be largely an iron-nickel…
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associating two items by pointing out their similarities. He used an apple for a literal comparison showing its similarity in shape to planet Earth. He showed how the apples indentations at top and bottom are similar to the effects of the magnetic fields in the North and South Pole. He then cut the apple in half to demonstrate by comparison the amount of Earth that is core just as the apple is mostly the fruit and not the skin. Another supporting device used by cannon is the use of testimony,…