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The Sun is the star at the center of the Solar System. It is a nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy mainly as light and infrared radiation. It is by far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometres (864,000 miles), or 109 times that of Earth, and its mass is about 330,000 times that of Earth. It accounts for about 99.86% of the total mass of the Solar System.
Roughly three quarters of the Sun's mass consists of hydrogen (~73%); the rest is mostly helium (~25%), with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.The Sun is a G-type main-sequence star (G2V) based on its spectral class. As such, it is informally and not completely accurately referred to as a yellow dwarf (its light is closer to white than yellow). It formed approximately 4.6 billion years ago from the gravitational collapse of matter within a region of a large molecular cloud. Most of this matter gathered in the center, whereas the rest flattened into an orbiting disk that became the Solar System. The central mass became so hot and dense that it eventually initiated nuclear fusion in its core. It is thought that almost all stars form by this process.
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Orsk (Russian: Орск, Kazakh: Жаманқала, romanized: Jamanqala) is the second largest city in Orenburg Oblast, Russia, located on the steppe about 100 kilometers (62 mi) southeast of the southern tip of the Ural Mountains. The city straddles the Ural River.
Tau Ceti f is a super-Earth or mini-Neptune orbiting Tau Ceti that was discovered in 2012 by...
Uppsala (, also US: or all ending in , Swedish: [ˈɵ̂pːˌsɑːla] (listen); archaically spelled...
Isla Mujeres (Spanish pronunciation: ['izla mu'xeɾes], Spanish for "Island of Women”...
York is a cathedral city and unitary authority area, at the confluence of the rivers Ouse and...