A star is a luminous ball of gas, mostly hydrogen and helium, held together by its own gravity. Viewed from Earth as it orbits the Sun, the apparent rotational period of the Sun at its equator is about 28 days. The Sun formed about 4.6 billion years ago from the collapse of part of a giant molecular cloud that consisted mostly of hydrogen and helium and that probably gave birth to many other stars. Instead, the moderate temperature range may be explained by a lower surface albedo brought about by less continental area and the lack of biologically induced cloud condensation nuclei. Sunspots are caused by complicated and not very well understood interactions with the Sun's magnetic field. When this alteration occurs the corona and the chromosphere change from being calm and somewhat quiet to activity that is violent. All waves except Alfvén waves have been found to dissipate or refract before reaching the corona. The magnetic polarity of sunspot pairs alternates every solar cycle, a phenomenon known as the Hale cycle. Credit: ESA/NASA. [92], The corona is the next layer of the Sun. [67] It has a density of up to 150 g/cm3[68][69] (about 150 times the density of water) and a temperature of close to 15.7 million kelvin (K). [69], The thermal columns of the convection zone form an imprint on the surface of the Sun giving it a granular appearance called the solar granulation at the smallest scale and supergranulation at larger scales. Estimates of the photon travel time range between 10,000 and 170,000 years. [42] Viewed from a vantage point above its north pole, the Sun rotates counterclockwise around its axis of spin. [210], An optical phenomenon, known as a green flash, can sometimes be seen shortly after sunset or before sunrise. Nuclear fusion reactions in its core support the star against gravity and produce photons and heat, as well as small amount… It also causes sunburn, and has other biological effects such as the production of vitamin D and sun tanning. The Sun Is Also a Star is a 2019 American teen drama film directed by Ry Russo-Young and written by Tracy Oliver, based on the young adult novel of the same name by Nicola Yoon.The film stars Yara Shahidi and Charles Melton, and follows a young couple who fall in love, while one of their families faces deportation.. In the 1st century AD, Ptolemy estimated the distance as 1,210 times the radius of Earth, approximately 7.71 million kilometers (0.0515 AU).[167]. For some periods of several decades, the motion is rather regular, forming a trefoil pattern, whereas between these periods it appears more chaotic. Similar effects are seen in the gas planets. Our Sun is a normal main-sequence G2 star, one of more than 100 billion stars in our galaxy. [25], The principal adjectives for the Sun in English are sunny for sunlight and, in technical contexts, solar /ˈsoʊlər/,[3] from Latin sol[26] – the latter found in terms such as solar day, solar eclipse and Solar System (occasionally Sol system). The Sun lies close to the inner rim of the Milky Way's Orion Arm, in the Local Interstellar Cloud or the Gould Belt, at a distance of 7.5–8.5 kiloparsecs (24–28 kly) from the Galactic Center. ( Sunspots can be very large, as much as 50,000 km in diameter. [58], The chemical composition of the photosphere is normally considered representative of the composition of the primordial Solar System. It is by far the most important source of energy for life on Earth. Take an interactive tour of the solar system, or browse the site to find fascinating information, facts, and data about our planets, the solar system, and beyond. The highly rarefied region above the chromosphere, called the corona, extends millions of kilometers into space but is visible only during a total solar eclipse (left). [197], The Indian Space Research Organisation has scheduled the launch of a 100 kg satellite named Aditya for mid 2020. It is 4.5 billion years old so that means we have 5 billion years from now until the sun will expand and destroy earth but we can't be … The Egyptians portrayed the god Ra as being carried across the sky in a solar barque, accompanied by lesser gods, and to the Greeks, he was Helios, carried by a chariot drawn by fiery horses. The minimum requirement of a life-supporting star … It has not changed dramatically for over four billion[a] years, and will remain fairly stable for more than five billion more. Solar System → Local Interstellar Cloud → Local Bubble → Gould Belt → Orion Arm → Milky Way → Milky Way subgroup → Local Group → Local Sheet → Virgo Supercluster → Laniakea Supercluster → Observable universe → UniverseEach arrow (→) may be read as "within" or "part of". {\displaystyle 2\Omega /\kappa \approx 1.50.} But just what is a star, exactly? In its core, it fuses hydrogen into helium, as all stars do for the majority of their lives, in order to generate enough pressure to avoid collapsing under its own gravity. [81] Presently, it is hypothesized (see Solar dynamo) that a magnetic dynamo within this layer generates the Sun's magnetic field. In 1666, Isaac Newton observed the Sun's light using a prism, and showed that it is made up of light of many colors. It will then expand more rapidly over about half a billion years until it is over two hundred times larger than today and a couple of thousand times more luminous. The enormous effect of the Sun on Earth has been recognized since prehistoric times, and the Sun has been regarded by some cultures as a solar deity. [174] The 19th century saw advancement in spectroscopic studies of the Sun; Joseph von Fraunhofer recorded more than 600 absorption lines in the spectrum, the strongest of which are still often referred to as Fraunhofer lines. From an observation of a transit of Venus in 1032, the Persian astronomer and polymath Ibn Sina concluded that Venus is closer to Earth than the Sun. 4 [23][24] This 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 ἥλιος hēlios, Welsh haul and Russian солнце solntse (pronounced sontse), as well as (with *l > r) Sanskrit स्वर svár and Persian خور xvar. Other stars with the same value of The Sun is the star at the center of the Solar System. Unfiltered binoculars can deliver hundreds of times as much energy as using the naked eye, possibly causing immediate damage. [28], The Sun is a G-type main-sequence star that comprises about 99.86% of the mass of the Solar System. Observations of sunspots were recorded during the Han Dynasty (206 BC–AD 220) by Chinese astronomers, who maintained records of these observations for centuries. This outermost layer of the Sun is defined to begin at the distance where the flow of the solar wind becomes superalfvénic—that is, where the flow becomes faster than the speed of Alfvén waves,[94] at approximately 20 solar radii (0.1 AU). [106], An 11-year sunspot cycle is half of a 22-year Babcock–Leighton dynamo cycle, which corresponds to an oscillatory exchange of energy between toroidal and poloidal solar magnetic fields. Heat is transferred outward from the Sun's core by radiation rather than by convection (see Radiative zone below), so the fusion products are not lifted outward by heat; they remain in the core[57] and gradually an inner core of helium has begun to form that cannot be fused because presently the Sun's core is not hot or dense enough to fuse helium. [175] Kelvin and Hermann von Helmholtz then proposed a gravitational contraction mechanism to explain the energy output, but the resulting age estimate was only 20 million years, well short of the time span of at least 300 million years suggested by some geological discoveries of that time. [98], High-energy gamma ray photons initially released with fusion reactions in the core are almost immediately absorbed by the solar plasma of the radiative zone, usually after traveling only a few millimeters. Only a very small fraction of the incident light is reflected. According to their system of classification, the Sun is known as a yellow dwarf star.This group of stars are relatively small, containing between 80% and 100% the mass of the Sun. 0 = [126] At present, it is increasing in brightness by about 1% every 100 million years. Ω A hopeless romantic ambivalent about his future in medical school falls for a hard-luck young woman who doesn't believe in love. The Evolution of a 3 M_{sun} Star from the Main Sequence Through Core Helium Burning". κ A FUMING prankster posing as a Star Wars character was forced to insist HE was the “real” Jawa after another joker copied him. How to choose your telescope magnification? Yes the Sun is a star, it is a yellow dwarf star. The Apex of the Sun's Way, or the solar apex, is the direction that the Sun travels relative to other nearby stars. At this point in the dynamo cycle, buoyant upwelling within the convective zone forces emergence of toroidal magnetic field through the photosphere, giving rise to pairs of sunspots, roughly aligned east–west and having footprints with opposite magnetic polarities. [52][73], The proton–proton chain occurs around 9.2×1037 times each second in the core, converting about 3.7×1038 protons into alpha particles (helium nuclei) every second (out of a total of ~8.9×1056 free protons in the Sun), or about 6.2×1011 kg/s. In a frame of reference defined by the stars, the rotational period is approximately 25.6 days at the equator and 33.5 days at the poles. Researchers recognize many different species in nine different taxonomic genuses. And since the Moon orbits the Earth in approximately the same plane as the Earth's orbit around the Sun sometimes the Moon comes directly between the Earth and the Sun. It was adopted as the Sabbath day by Christians who did not have a Jewish background. Watch The Sun is Also a Star [2019] Streaming Online. This motion of the Sun is mainly due to Jupiter, Saturn, Uranus, and Neptune. is 222 million years, the value of We see themon most clear nights as tiny, twinkling pinpricks of light in the sky. These meteorites are thought to retain the composition of the protostellar Sun and are thus not affected by settling of heavy elements. The thermal pulses become larger each time, with the later pulses pushing the luminosity to as much as 5,000 times the current level and the radius to over 1 AU. / These probes orbited the Sun at a distance similar to that of Earth, and made the first detailed measurements of the solar wind and the solar magnetic field. MyPillow CEO pushes conspiracy theory at WH. Eddington, who gave us the standard solar model, did so using gravity and ideal gas laws. The Sun serves as a laboratory for the study of plasma physics, i.e., the study of the interactions between ionized gas and magnetic fields. [31] The formation of the Sun may have been triggered by shockwaves from one or more nearby supernovae. The Solar Maximum Mission subsequently acquired thousands of images of the solar corona before re-entering Earth's atmosphere in June 1989. Averroes also provided a description of sunspots in the 12th century. Learn about the important relationship between Earth and the sun. Models that have higher mass loss on the red-giant branch produce smaller, less luminous stars at the tip of the asymptotic giant branch, perhaps only 2,000 times the luminosity and less than 200 times the radius. It will then have reached the red clump or horizontal branch, but a star of the Sun's mass does not evolve blueward along the horizontal branch. [47] Solar ultraviolet radiation ionizes Earth's dayside upper atmosphere, creating the electrically conducting ionosphere.[48]. [90], Above the chromosphere, in a thin (about 200 km) transition region, the temperature rises rapidly from around 20000 K in the upper chromosphere to coronal temperatures closer to 1000000 K.[91] The temperature increase is facilitated by the full ionization of helium in the transition region, which significantly reduces radiative cooling of the plasma. [179] In 1920, Sir Arthur Eddington proposed that the pressures and temperatures at the core of the Sun could produce a nuclear fusion reaction that merged hydrogen (protons) into helium nuclei, resulting in a production of energy from the net change in mass. This enables stereoscopic imaging of the Sun and solar phenomena, such as coronal mass ejections. [91], Theoretical models of the Sun's development suggest that 3.8 to 2.5 billion years ago, during the Archean eon, the Sun was only about 75% as bright as it is today. km/s, and estimates for the other constants are A = 15.5 km/s/kpc, B = −12.2 km/s/kpc, κ = 37 km/s/kpc, and ν=74 km/s/kpc. This star just happens to be named "Sun" (technically, the name for our residential star is Sol). It was the center of a popular cult among Romans, who would stand at dawn to catch the first rays of sunshine as they prayed. We take X(0) and Y(0) to be zero and Z(0) is estimated to be 17 parsecs. [27], The English weekday name Sunday stems from Old English Sunnandæg "sun's day", a Germanic interpretation of the Latin phrase diēs sōlis, itself a translation of the Greek ἡμέρα ἡλίου hēmera hēliou "day of the sun". Slowly changing high-speed streams of solar wind are emitted from coronal holes at the photospheric surface. The change in opacity is due to the decreasing amount of H− ions, which absorb visible light easily. For many years measurements of the number of neutrinos produced in the Sun were lower than theories predicted by a factor of 3. The composition of the solar wind also appears to differ in the polar regions. Just a few months after launch, however, an electronics failure caused the probe to go into standby mode, and it spent the next three years in this inactive state. The photosphere is not fully ionized—the extent of ionization is about 3%, leaving almost all of the hydrogen in atomic form. The Solar System also has at least five dwarf planets, an asteroid belt, numerous comets, and a large number of icy bodies which lie beyond the orbit of Neptune. In this layer, the solar plasma is not dense enough or hot enough to transfer the heat energy of the interior outward via radiation. It is, however, larger than most (although not the biggest) and a very special star to us. [92] Skylab made the first time-resolved observations of the solar transition region and of ultraviolet emissions from the solar corona. ) 7.17 [112] The effects of solar activity on Earth include auroras at moderate to high latitudes and the disruption of radio communications and electric power. The Sun’s surface area is 11,990 times that of the Earth’s. This is the time it would take the Sun to return to a stable state, if the rate of energy generation in its core were suddenly changed. [194], The Solar Terrestrial Relations Observatory (STEREO) mission was launched in October 2006. Ω All these words stem from Proto-Germanic *sunnōn. [125] The Sun is gradually becoming hotter during its time on the main sequence, because the helium atoms in the core occupy less volume than the hydrogen atoms that were fused. Instead of five arms, the various species in this family have many arms. [71][72], The core is the only region in the Sun that produces an appreciable amount of thermal energy through fusion; 99% of the power is generated within 24% of the Sun's radius, and by 30% of the radius, fusion has stopped nearly entirely. Simple filters made of darkened glass allow the full intensity of sunlight to pass through if they break, endangering the observer's eyesight. [178] However, it would be Albert Einstein who would provide the essential clue to the source of the Sun's energy output with his mass–energy equivalence relation E = mc2. [132] According to a 2008 model, Earth's orbit is shrinking due to tidal forces (and, eventually, drag from the lower chromosphere), so that it will be engulfed by the Sun near the tip of the red giant branch phase, 3.8 and 1 million years after Mercury and Venus have respectively had the same fate. Rather, it forms a kind of nimbus around chromospheric features such as spicules and filaments, and is in constant, chaotic motion. Despite its typical whiteness, most[note 1] people mentally picture the Sun as yellow; the reasons for this are the subject of debate. [14] The result is consistent with the radiometric date of the oldest Solar System material, at 4.567 billion years ago. The differential rotation extends considerably down into the interior of the Sun but the core of the Sun rotates as a solid body. Some improvised filters that pass UV or IR rays, can actually harm the eye at high brightness levels. π [128][129] As a red giant, the Sun will grow so large that it will engulf Mercury, Venus, and probably Earth. V / The central mass became so hot and dense that it eventually initiated nuclear fusion in its core. The Sun has an absolute magnitude of +4.83, estimated to be brighter than about 85% of the stars in the Milky Way, most of which are red dwarfs. The Sun is by far the brightest object in the Earth's sky, with an apparent magnitude of −26.74. [225] The sun goddess Amaterasu is the most important deity in the Shinto religion,[226][227] and she is believed to be the direct ancestor of all Japanese emperors.[226]. But since the path of totality is so small it is very unlikely that it will cross you home. That's true in the sense that there are many others similar to it. The largest sunspots can be tens of thousands of kilometers across. {\displaystyle 2\pi /\Omega _{0}} [100], Neutrinos are also released by the fusion reactions in the core, but, unlike photons, they rarely interact with matter, so almost all are able to escape the Sun immediately. The flash is caused by light from the Sun just below the horizon being bent (usually through a temperature inversion) towards the observer. One theory among scientists is that the atmosphere of the young Earth contained much larger quantities of greenhouse gases (such as carbon dioxide, methane) than are present today, which trapped enough heat to compensate for the smaller amount of solar energy reaching it. [213] The ancient Sumerians believed that the Sun was Utu,[214][215] the god of justice and twin brother of Inanna, the Queen of Heaven,[214] who was identified as the planet Venus. In the overall gloom, the pupil expands from ~2 mm to ~6 mm, and each retinal cell exposed to the solar image receives up to ten times more light than it would looking at the non-eclipsed Sun. But there are many more smaller stars than larger ones; the Sun is in the top 10% by mass. Christian churches were built with an orientation so that the congregation faced toward the sunrise in the East. The Sun is a huge mass of hot, glowing gas. In the early years of the modern scientific era, the source of the Sun's energy was a significant puzzle. Instead it will exit the main sequence in approximately 5 billion years and start to turn into a red giant. The sun's surface temperature is … [115] Such a weak star would not have been able to sustain liquid water on Earth's surface, and thus life should not have been able to develop. The Sun will spend a total of approximately 10 billion years as a main-sequence star. [67] Through most of the Sun's life, energy has been produced by nuclear fusion in the core region through a series of nuclear reactions called the p–p (proton–proton) chain; this process converts hydrogen into helium. Pluto is no longer officially a planet but we'll keep it here for history's sake.). How does the variability of the Sun affect the Earth's climate? [80], The radiative zone and the convective zone are separated by a transition layer, the tachocline. [44] Sunlight on the surface of Earth is attenuated by Earth's atmosphere, so that less power arrives at the surface (closer to 1,000 W/m2) in clear conditions when the Sun is near the zenith. The heavy elements could most plausibly have been produced by endothermic nuclear reactions during a supernova, or by transmutation through neutron absorption within a massive second-generation star.[31]. For a simple dipolar solar magnetic field, with opposite hemispherical polarities on either side of the solar magnetic equator, a thin current sheet is formed in the solar wind. It has been argued that the Sun's passage through the higher density spiral arms often coincides with mass extinctions on Earth, perhaps due to increased impact events. [69] Ions of hydrogen and helium emit photons, which travel only a brief distance before being reabsorbed by other ions. [46] The atmosphere in particular filters out over 70% of solar ultraviolet, especially at the shorter wavelengths. [129] For the Sun, four thermal pulses are predicted before it completely loses its outer envelope and starts to make a planetary nebula. The Sun is sometimes referred to as a “typical” or “average” star. Our Sun is 864,000 miles in diameter and 10,000 degrees Fahrenheit on the surface. It is calculated that the Sun will become sufficiently large to engulf the current orbits of Mercury and Venus, and render Earth uninhabitable – but not for about five billion years. The strong gravitational pull of the Sun holds Earth and the other planets in the solar system in orbit.