Sun

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. The synodic rotation of Earth and its orbit around the Sun are the basis of solar calendars. The English word sun developed from Old English sunne.

About Sun in brief

Summary Sun 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. Its diameter is about 1.39 million kilometres, and its mass is about 330,000 times that of Earth. The Sun has been regarded by some cultures as a deity. The synodic rotation of Earth and its orbit around the Sun are the basis of solar calendars, one of which is the predominant calendar in use today. The English word sun developed from Old English sunne. In English, the Greek and Latin words occur in poetry as personifications of the Sun. In science fiction, the term Sol may be used as a name for the Sun to distinguish it from other stars. The term’sol’ with a lower-case’sols’ is used by planetary astronomers for the duration of a solar day on another planet such as Mars. In technical contexts, the latter comes from Latin sol –r, from the latter found in terms such as solar eclipse and solar day. From the Greek word helios comes the rare adjective heliacˈhiːkli, which means ‘day of the sun’ The name Sunday stems from the Old English Sunnandæs, a weekday name for Sunday. The word sun is ultimately related to the word for ‘sun’ in other branches of the Indo-European language family, though in most cases a nominative stem with an l is found, rather than the genitive stem in n, as for example in Latin sōl, Greek hēlios, Welsh haul and Russian солнце solntse.

In other Germanic languages, including West Frisian sinne, Dutch zon, Low German Sünn, Standard German Sonne, Bavarian Sunna, Old Norse sunna and Gothic sunnō, the words for “sun” and “solar” are found in Swedish and Danish solen, Icelandic sólin, etc. The name ‘sol’ comes from the Latin phrase ‘sōl’, which is a translation of the phrase “ sun’s day’. The sun is a G-type main-sequence star based on its spectral class. As such, it is informally and not completely accurately referred to as a yellow dwarf. 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. Roughly three quarters of Sun’s mass consists of hydrogen ; the rest is mostly helium, with much smaller quantities of heavier elements, including oxygen, carbon, neon, and iron.