The sun is the star in the center of the Solar System. It is a nearly perfect thermal plasma ball, with an internal convective movement that generates a magnetic field through a dynamo process. So far the most important source of energy for life on Earth. Its diameter is about 1.39 million kilometers, 109 times from Earth, and its mass is about 330,000 times Earth, accounting for 99.86% of the total mass of the Solar System. About three-quarters of the Sun's mass consists of hydrogen (~ 73%); the rest is mostly helium (~ 25%), with smaller amounts of heavier elements, including oxygen, carbon, neon, and iron.
The Sun is the main sequence star G-type (G2V) based on its spectral class. Thus, it is informally and not fully accurately referred to as a yellow dwarf (the light is closer to white than yellow). It formed about 4.6 billion years ago from the gravitational collapse of matter within a large molecular cloud region. Most of this material is gathered in the middle, while the rest is leveled into orbiting disks that become the Solar System. The central mass becomes so hot and dense that it eventually starts nuclear fusion at its core. It is estimated that almost all stars are formed by this process.
The sun is about middle-aged; it has not changed dramatically for over four billion years, and will remain stable for over five billion years. Currently fuzes about 600 million tons of hydrogen into helium every second, converting 4 million tons of matter into energy every second as a result. This energy, which can take between 10,000 and 170,000 years to escape from its core, is the source of light and heat of the Sun. In about 5 billion years, when the fusion of hydrogen in its core has diminished to the point where the Sun is no longer in hydrostatic equilibrium, the Sun's core will experience a noticeable increase in density and temperature while its outer layer extends until it becomes a red giant. It is thought that the Sun will be large enough to engulf the current orbit of Mercury and Venus, and make Earth uninhabitable. After this, it releases its outer layer and becomes a solid type of cooling star known as a white dwarf, which no longer produces energy by fusion, but still shines and releases heat from the previous mix.
The great effects of the Sun on Earth have been recognized since prehistoric times, and the Sun has been regarded by some cultures as gods. The sinodic rotation of the Earth and its orbit around the Sun is the basis of the solar calendar, one of which is the dominant calendar used today.
Video Sun
Name and etymology
The actual English name Sun is developed from Old English sunne and may be related to south . Cognition into English sun appears in other Germanic languages, including Old Frisian sunne , sonne , Old Saxon sunna , Middle Dutch Dutch sonne , modern Dutch zon , Old High German sunna , modern German Sonne , Old Norse sunna , and Gothic sunn? . All German terms for Sun come from Proto-Germanic * sunn? N .
The Latin name for the Sun, Sol , is used at times as another name for the Sun, but is not commonly used in everyday English. Sol is also used by planetary astronomers to refer to the duration of a solar day on other planets, such as Mars.
The related word solar is an adjective term commonly used for the Sun, in terms of solar day, solar eclipse, and the Solar System. Earth's average solar time is about 24 hours, while the average 'sol' of Mars is 24 hours, 39 minutes, and 35,244 seconds.
The name of the English Sunday week begins with Old English ( SunnandÃÆ'Â|g ; "Day of the Sun", from before 700) and is ultimately the result of German language interpretation of the language Latin > dies solis , the Greek translation ????? ????? ( h? mÃÆ' Â © ra h? lÃÆ'ou ).
Religious aspects
The solar gods play a major role in many world religions and mythologies. The ancient Sumerians believed that the sun was Utu, the god of justice and the twin brother of Inanna, Queen of Heaven, identified as the planet Venus. Later, Utu was identified with the Eastern Semitic god Shamash. Utu is regarded as a helper deity, who helps those who suffer, and, in iconography, he is usually depicted with a long beard and a saw wield, representing his role as a dealer of justice.
From at least the Fourth Dynasty of Ancient Egypt, the Sun was worshiped as the god Ra, depicted as a hawk-headed god overcome by a solar disk, and surrounded by snakes. In the New Empire period, the Sun is identified with a dung beetle, whose round ball of dung is identified with the Sun. In the form of the Sun Aten disk, the Sun undergoes a brief resurgence during the Amarna Period when it again becomes the best, if not only, divinity for Pharaoh Akhenaton.
In Proto-Indo-European religion, the sun is personified as a goddess * Seh 2 ul . Derivatives of this goddess in the Indo-European languages ​​include Old Norse SÃÆ'³l , Sanskrit Solar , Gaulish Sulis , Lithuania Saul? , and Slavic Solntse . In the ancient Greek religion, the sun god was the male deity of Helios, but the traces of the female sun god were previously preserved in Helen of Troy. Later, Helios synced with Apollo.
In the Bible, Malachi 4: 2 mentions "Sun of Righteousness" (sometimes translated as "Sun of Justice"), which some Christians interpret as reference to the Messiah (Christ). In ancient Roman culture, Sunday is the day of the sun god. It was adopted as a Sabbath by Christians who had no Jewish background. The symbol of light is a pagan device adopted by Christians, and perhaps most importantly not originating from Jewish tradition. In paganism, the Sun is the source of life, giving warmth and illumination to mankind. It was a popular worship center among the Romans, who would stand at dawn to capture the first rays of sunshine as they prayed. The celebration of the winter soltice (which affects Christmas) is part of the invincible Roman cult of the Sun (Sol Invictus). The Christian churches are built with orientation so that the congregation is faced with the rising sun in the East.
Tonatiuh, the Aztec sun god, is usually described as holding arrows and shields and is closely related to the practice of human sacrifice. The sun goddess Amaterasu is the most important deity in Shinto religion, and he is believed to be the direct ancestor of all the Japanese emperors.
Maps Sun
Characteristics
The Sun is a G-type main sequence consisting of about 99.86% of the mass of the Solar System. The sun has an absolute magnitude of 4.83, estimated to be brighter than about 85% of stars in the Milky Way, most of which are red dwarfs. The Sun is the Star of Population I, or the rich-rich-element. The formation of the Sun may have been triggered by shock waves from one or more nearby supernovae. This is suggested by the high abundance of heavy elements in the Solar System, such as gold and uranium, relative to the abundance of these elements in so-called Population II, star-poor-weight, stars. The most plausible heavy elements have been generated by endothermic nuclear reactions during supernovae, or by transmutation through the absorption of neutrons in a massive second generation star.
The Sun is by far the brightest object in the Earth's sky, with an apparent magnitude of -26.74. It's about 13 billion times brighter than the next bright star, Sirius, who has a visible -1.46 magnitude. The average distance of the center of the Sun to the center of the Earth is about 1 unit of astronomy (about 150,000,000 km, 93,000,000 mi), although the distance varies as the Earth moves from perihelion in January to aphelion in July. At this average distance, light moves from the sun's horizon to the horizon of the Earth in about 8 minutes and 19 seconds, while light from the nearest points of the Sun and Earth takes about two seconds less. This solar energy supports almost all life on Earth with photosynthesis, and encourages Earth's climate and weather.
The sun has no definite limits, but its density decreases exponentially with increasing height above the photosphere. For measurement purposes, however, the radius of the Sun is regarded as the distance from its center to the edge of the photosphere, the visible surface of the Sun. With this measure, the Sun is an almost perfect ball with an estimated oblateness of about 9 million, meaning the polar diameter is different from the equatorial diameter of only 10 kilometers (6.2 miles). The tidal effects of the planets are weak and do not affect the shape of the Sun significantly. The sun spins faster at the equator than at the poles. This differential rotation is caused by convective motion due to heat transport and Coriolis forces due to the rotation of the Sun. In terms of reference specified by the stars, the rotation period is approximately 25.6 days at the equator and 33.5 days at the poles. Seen from the Earth as it orbits the Sun, the sun's clear rotation period at the equator is about 28 days.
Sunlight
The solar constant is the amount of power stored by the Sun per unit area that is directly exposed to sunlight. The solar constant equals about 1,368 W/m 2 (watts per square meter) at the distance of one astronomical unit (AU) from the Sun (ie, on or near Earth). Sunlight on Earth's surface is attenuated by Earth's atmosphere, so less power arrives at the surface (closer to 1,000 W/m 2 ) in clear conditions when the Sun is near zenith. Sunlight in the upper atmosphere of the Earth is composed (with total energy) of about 50% of infrared light, 40% visible light, and 10% of ultraviolet light. The atmosphere typically filters more than 70% of the ultraviolet sun, especially at shorter wavelengths. Ultraviolet radiation of the sun ionizes the upper atmosphere of Earth's day, creating an ionosphere that brings electricity.
The color of the Sun is white, with the CIE color-space close index (0.3, 0.3), when viewed from space or when the Sun is high in the sky. When measuring all the emitted photons, the Sun actually emits more photons in the green part of the spectrum than others. When the Sun is low in the sky, atmospheric scattering makes the Sun yellow, red, orange, or magenta. Although white is typical, most people mentally imagine the sun as yellow; the reason for this is the subject of debate. The Sun is a star G2V, with G2 which shows its surface temperature around 5.778Ã, Â ° K (5,505 Â ° C, 9,941 Â ° F), and V it has. , like most stars, are the main sequential stars. The average luminance of the Sun is about 1.88 giga candela per square meter, but when viewed through Earth's atmosphere, it is lowered to about 1.44 Gcd/m 2 . However, the luminance is not constant in the solar disk (embezzlement branch).
Composition
The Sun consists primarily of chemical elements of hydrogen and helium. At this time in Sun's life, they account for 74.9% and 23.8% of the Sun's mass in the photosphere, respectively. All the heavier elements, called metal in astronomy, account for less than 2% of the mass, with oxygen (about 1% of the Sun's mass), carbon (0.3%), neon (0, 2%), and iron (0.2%) became the most abundant.
The original chemical composition of the Sun is inherited from the interstellar medium formed from it. The original will contain about 71.1% hydrogen, 27.4% helium, and 1.5% more heavy elements. Hydrogen and most of the helium in the Sun will be generated by the Big Bang nucleosynthesis in the first 20 minutes of the universe, and heavier elements are generated by previous star generations before the Sun is formed, and spread to the interstellar medium. during the last stages of the life of stars and by events such as supernovas.
Since the Sun is formed, the main fusion process has involved fuzing hydrogen into helium. Over the past 4.6 billion years, the amount of helium and its location in the Sun has gradually changed. In the core, the proportion of helium has increased from about 24% to about 60% due to fusion, and some helium and heavy elements have settled from the photosphere toward the center of the Sun because of gravity. The proportion of metals (heavy elements) has not changed. Heat is transferred out of the Sun's core by radiation rather than by convection (see Radiative zone below), so that the fusion product is not lifted out by heat; they remain in the core and gradually the core of the helium nucleus has begun to form which can not converge because now the Sun's core is not hot or solid enough to combine helium. In the current photosphere the helium fraction decreases, and metallicity is only 84% of what is in the protostellar phase (before nuclear fusion at the nucleus begins). In the future, helium will continue to accumulate in its core, and in about 5 billion years, this gradual buildup will eventually cause the Sun out of the main sequence and become a red giant.
The chemical composition of the photosphere is usually considered to represent the composition of the primordial Solar System. The abundance of the solar-weight element described above is usually measured either by using spectroscopy from the solar photosphere and by measuring abundance in meteorites that have never been heated until the melting temperature. This meteorite is thought to retain the protostellar solar composition and is thus unaffected by heavy element precipitation. Both methods generally agree well.
Single ionized iron group elements
In the 1970s, many studies focused on the abundance of iron elements in the Sun. Although significant research has been done, until 1978 it was difficult to determine the abundance of some iron group elements (eg cobalt and manganese) through spectrography because of their hyperfine structure.
The first major set of oscillator strengths of single ionized iron ion elements was made available in the 1960s, and this was later rectified. In 1978, the abundance of single ionization elements of the iron group originated.
Isotope composition
Various authors have considered the existence of gradients in the isotopic composition of the solar and planetary super gases, for example the correlation between the composition of neon isotopes and xenon in the Sun and on the planets.
Before 1983, it was thought that the entire Sun had the same composition as the sun's atmosphere. In 1983, he claimed that fractionation in the Sun itself caused the isotope-composition relationship between the planet's noble and solar-wind-implanted gases.
Structure and energy production
The structure of the Sun contains the following layers:
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- Core - most within 20 - 25% of the radius of the Sun, where temperature (energy) and pressure are sufficient for nuclear fusion. Hydrogen fuzes become helium (which today can not be confused at this point in Sun's life). The fusion process releases energy, and helium accumulates gradually to form the core of the helium nucleus within the nucleus itself.
- Zone of radiation - convection can not occur until closer to the surface of the Sun. Therefore between about 20-25% radius, and 70% radius, there is a "radiation zone" where the transfer of energy occurs through radiation (photons) rather than by convection.
- Tachocline - boundary area between the radiation zone and the convective.
- Convective zone - Between about 70% of the radius of the Sun and a point close to the visible surface, the Sun is cold and sufficiently diffuse for convection, and this being the primary means of heat transfer, similar with weather cells formed in Earth's atmosphere.
- Photosphere - the deepest part of the Sun that we can observe directly with visible light. Because the Sun is a gas object, it has no clear surface; the visible part is usually divided into 'photosphere' and 'atmosphere'.
- Atmosphere - "circles" the gas surrounding the Sun, which consists of the chromosphere, the sun transition region, the corona and the heliosphere. This can be seen when the main part of the Sun is hidden, for example, during a solar eclipse.
Core
The core of the Sun extends from the center to about 20-25% of the radius of the sun. It has a density up to 150 g/cm 3 (about 150 times the water density) and the temperature is close to 15.7 million kelvin (K). In contrast, the surface temperature of the Sun is about 5,800 K. The latest analysis of the SOHO mission data supports a faster rotation rate in the core than in the radiation zone above. Through much of the life of the Sun, energy has been generated by nuclear fusion in the core region through a series of steps called p-p chains (protons); this process converts hydrogen into helium. Only 0.8% of the energy produced in the Sun comes from the CNO cycle, although this proportion is expected to increase as the Sun becomes older.
The nucleus is the only region in the Sun that produces large amounts of heat energy through fusion; 99% of the power is generated in 24% of the radius of the Sun, and with 30% radius, the fusion has stopped almost entirely. The rest of the Sun is heated by this energy because it is moved out through many successive layers, eventually into a solar phototherapy where it releases into space as sunlight or kinetic energy of particles.
The proton-proton chain occurs around 9.2 ÃÆ' - 10 37 times every second in the core, turning around 3.7 ÃÆ' - 10 38 proton becomes an alpha particle (helium nuclei) every second (from total ~ 8.9 ÃÆ' - 10 56 Free proton in the Sun), or about 6.2 ÃÆ' - 10 11 kg/s. Combining four free protons (hydrogen nuclei) into single alpha particles (helium nuclei) releases about 0.7% of the mass that converges as energy, so that the Sun releases energy at a mass-energy conversion rate of 4.26 million metric tons per second (requiring 600 megaton metric hydrogen), for 384.6 yottawatts ( 3,846 ÃÆ' - 10 26 Ã, W ), or 9,192 ÃÆ'â € " 10 10 Ã, megaton TNT per second. However, the large power output from the Sun is mainly due to large size and core density (compared to earth and earth objects), with only a small amount of power generated per cubic meter. The theoretical model of the interior of the Sun shows a power density, or energy production, of about 276.5 watts per cubic meter, which is roughly equal to the rate of electricity production occurring in reptile metabolism or compost piles.
The melting rate in the core is in the self-correcting balance: slightly higher fusion levels will cause the core to overheat and extend slightly to the outer layer weight, reduce the density and hence the melting rate and correct the disturbance; and a slightly lower level will cause the core to cool down and shrink slightly, increase the density and increase the melting rate and return it back to the current rate.
Radiation zone
From the core to about 0.7 solar radii, thermal radiation is the main means of energy transfer. Temperatures fall from about 7 million to 2 million kelvins with distances farther from the core. This temperature gradient is less than the adiabatic hose level and therefore can not induce convection, which explains why energy transfer through this zone is by radiation, not thermal convection. Hydrogen and hydrogen ions emit photons, which travel only a short distance before being reabsorbed by other ions. Density decreases a hundredfold (from 20 g/cm 3 to 0.2 g/cm 3 ) from 0.25 fingers of the sun to 0.7 radii , the top of the radiation zone.
Tachocline
Zones of radiation and convective zones are separated by a transitional layer, tachocline. This is the area where the sharp regime change between the uniform rotation of the radiation zone and the differential rotation of the convection zone produces a large shear between the two - a condition in which the horizontal layers successively glide past each other. Currently, it is hypothesized (see the solar dynamo) that the magnetic dynamo in this layer produces the Sun's magnetic field.
Convective zone
The solar convection zone extends from 0.7 solar radii (500,000 km) to near surface. In this layer, the solar plasma is not solid enough or hot enough to transfer heat energy from the interior to the outside through radiation. In contrast, plasma density is low enough to allow convective currents to develop and move the Sun's energy outward toward its surface. The heated material in the tachocline takes heat and expands, thus reducing the density and allowing it to rise. As a result, the regular movement of the mass develops into thermal cells that carry most of the heat out into the Sun's photosphere above. After the material spreads and radiologically cools just below the photospheric surface, its density increases, and sinks to the bottom of the convection zone, where it recovers heat from the top of the radiation zone and the continuing convective cycle. In the photosphere, the temperature has dropped to 5,700 K and the density is only 0.2 g/m 3 (about 1/6,000 air density at sea level).
The thermal column of the convection zone forming a trace on the surface of the Sun provides a granular appearance called solar granulation at the smallest scale and supergranulation on a larger scale. The turbulent convection in the outer interior of the sun supports the small-scale dynamo action above the near-surface volume of the Sun. The Sun's thermal column is a BÃÆ' Â © nard cell and takes the form of a hexagonal prism.
Photosphere
The visible Sun surface, the photosphere, is the layer below which the Sun becomes blurred into visible light. Above photosphere visible free sunlight spread into space, and almost all energy releases the Sun completely. Opacity changes are caused by a decrease in the amount of H - ion, which absorbs visible light easily. Instead, the visible light that we see is generated when the electrons react with the hydrogen atom to produce H - ions. The photosphere is tens to hundreds of kilometers thick, and a little less opaque than the air on Earth. Since the top of the photosphere is colder than the bottom, the image of the Sun is lighter in the center than at the edges or limbs of the solar disk, in a phenomenon known as embezzlement of branches. The spectrum of sunlight has about a spectrum of black body radiation at about 6,000 K, interspersed with an atomic absorption pathway from the tenuous layers above the photosphere. The photosphere has a particle density of ~ 23 m -3 (about 0.37% of the number of particles per volume of Earth's atmosphere at sea level). The photosphere is not fully ionized - the extent to which ionization is about 3%, leaving almost all hydrogen in the form of atoms.
During the initial study of the optical spectrum of the photosphere, several absorption lines were found that did not match the known chemical elements on Earth. In 1868, Norman Lockyer hypothesized that this absorption path was caused by a new element which he called helium, after the Greek sun god Helios. Twenty-five years later, helium is isolated on Earth.
Atmosphere
During a total solar eclipse, when the Sun disk is covered by the Moon, parts of the Sun's atmosphere can be seen. It consists of four distinct parts: the chromosphere, the transition region, the corona and the heliosphere.
The coolest layer of the Sun is the minimum area temperature that extends to about 500Ã, km above the photosphere, and has a temperature of about 4.100Ã, K . This part of the Sun is cool enough to allow for the existence of simple molecules such as carbon monoxide and water, which can be detected through their absorption spectrum.
The chromosphere, transition region, and corona are much hotter than the surface of the Sun. The reason is not well understood, but evidence suggests that Alfn waves may have enough energy to heat up the corona.
Above the minimum layer of temperature is a thick layer 2.000Ã, km , dominated by emission spectrum and absorption path. This is called chromosphere of the Greek root chroma , which means color, because the chromosphere is seen as a colored flash at the beginning and end of the total solar eclipse. The chromosphere temperature increases gradually with altitude, ranging up to about 20,000 K near the top. At the top of the chromosphere helium becomes partly ionized.
Above the chromosphere, in a thin transition region (about 200 km), the temperature rises rapidly from about 20,000 K in the upper chromosphere to a coronal temperature closer to 1,000,000 K. The increase in temperature is facilitated by full ionization of helium in the transition region, which is significantly reduce the cooling of plasma radiation. The transition region does not occur at well-defined altitudes. Instead, it forms a kind of nimbus around the chromosphere features such as spicules and filaments, and in constant and chaotic movements. The transition region is not easily visible from the Earth's surface, but is easily observed from outer space by instruments sensitive to extreme ultraviolet parts of the spectrum.
The corona is the next layer of the Sun. Low corona, near the surface of the Sun, has a particle density of about 10 15 m -3 to 10 16 m -3 . The average temperature of the corona and solar wind is about 1,000,000-2,000,000K; However, in the hottest regions it is 8,000,000-20,000,000K. Although there is no complete theory to take into account corona temperatures, at least some of the heat is known to come from magnetic reconnection. The corona is the long atmosphere of the Sun, which has a volume much larger than the volume covered by the solar photosphere. The plasma flow out of the Sun into interplanetary space is the solar wind.
The heliosphere, the fragile outer atmosphere of the Sun, is filled with solar wind plasma. This outer layer of the Sun is defined to begin at the distance where the solar wind flow becomes superalfvÃÆ' Â © nic - that is, where the flow becomes faster than the Alfe wave speed, at about 20 solar radii (0, 1 AU). Turbulence and dynamic forces in the heliosphere can not affect the shape of the sun's corona inside, because information can only run at Alfe's wave speed. The solar wind moves out continuously through the heliosphere, forming the sun's magnetic field into a spiral shape, until it impacts the heliopause of more than 50 AUs from the Sun. In December 2004, the Voyager 1 probe passed through the front that was considered part of a heliopause. At the end of 2012 Voyager 1 recorded a sharp rise in cosmic ray collisions and a sharp decline of lower energy particles from the solar wind, indicating that the probe had passed through heliopause and entered the interstellar medium.
Photons and neutrinos
The high-energy gamma-ray photons that were originally released with fusion reactions in the core were almost immediately absorbed by the solar plasma from the radiation zone, usually after walking just a few millimeters. Re-emission occurs randomly and usually with a slightly lower energy. With this sequence of emissions and absorption, it takes a long time for radiation to reach the surface of the Sun. The approximate photon travel time is between 10,000 and 170,000 years. Instead, it takes just 2.3 seconds for the neutrino, which accounts for about 2% of the total solar energy production, to reach the surface. Because the energy transport in the Sun is a process involving photons in the thermodynamic equilibrium with matter, the energy transport time scale in the Sun is longer, at the order of 30,000,000 years. This is the time it takes the Sun to return to a stable state, if the rate of generation of energy in its essence suddenly changes.
Neutrinos are also released by fusion reactions in the nucleus, but, unlike photons, they rarely interact with matter, so almost all can escape from the Sun immediately. For years the measurement of the number of neutrinos produced in the Sun was lower than the theory predicted by factor 3. This difference was solved in 2001 through the discovery of the neutrino oscillation effect: The sun emits the number of neutrino predicted by theory, but the neutrino detector is lost < soup> 2 / 3 from them because neutrinos have changed taste when they were detected.
Magnets and activities
Magnetic field
The sun has a magnetic field that varies across the surface of the Sun. The polar fields are 1-2 gauss (0.0001-0,0002Ã, T), whereas the field is usually 3,000 gauss (0.3Ã, T) in features on the Sun called sunspots and 10-100 gauss (0.001-0.01 T ) in the sun stands out.
Magnetic fields also vary in time and location. The 11 year quasi-periodic solar cycle is the most prominent variation in which the number and size of sunspots decreases and decreases.
Sunspots are seen as dark patches in the solar photosphere, and correspond to the concentration of magnetic fields where convective heat transport is inhibited from the sun's interior to the surface. As a result, sunspots are slightly colder than the surrounding photosphere, and, so, they look dark. At a minimum of a regular sun, some sunspots are visible, and sometimes nothing can be seen at all. Those who appear are in high sun latitudes. When the solar cycle lasts to a maximum, sunspots tend to form closer to the equator of the sun, a phenomenon known as the SpÃÆ'¶rer law. The largest sun point can reach tens of thousands of kilometers.
The 11-year sunspot cycle is half of the 22-year cycle of the Babcock-Leighton dynamo, which corresponds to the exchange of oscillatory energy between the toroidal and poloidal solar magnetic fields. In the maximum solar cycle, the external poloonal dipolar magnetic field is close to the minimum power of the dynamo-cycle, but the internal toroidal quadrupolar field, generated through differential rotation within the tachocline, is near its maximum strength. At this point in the dynamo cycle, buoyant upwelling within the convection zone forces the appearance of the toroidal magnetic field through the photosphere, resulting in pairs of sunspots, roughly aligned east-west and having footprints with opposite magnetic polarities. The magnetic polarity of the sunspot pair alternates each solar cycle, a phenomenon known as the Hale cycle.
During the phase of the sun's cycle decline, energy shifts from the internal toroidal magnetic field to an external polo field, and sunspots are reduced in number and size. At a minimum of solar cycles, the toroidal plane, thus, at minimum strength, sunspots is relatively rare, and the poloid plane is at its maximum strength. With the advent of the next 11-year sunspot cycle, the differential rotation shifts the magnetic energy back from the poloid to the toroidal plane, but with the polarity opposite to the previous cycle. The process continues, and in an ideal, simplified scenario, every 11-year sunspot cycle corresponds to change, then, in the overall polarity of the large-scale magnetic field of the Sun.
The sun's magnetic field extends beyond the Sun itself. The electrically conducting solar wind plasma brings the Sun's magnetic field into space, forming so-called interplanetary magnetic fields. In an approach known as ideal magnetohydrodynamics, the plasma particles move only along the lines of the magnetic field. As a result, the solar wind that flows outwards stretches the external intercellular field, forcing into rough radial structures. For a simple dipolar solar magnetic field, with opposite polarity poles on both sides of the solar magnetic equator, thin current sheets are formed in the solar wind. At great distances, the rotation of the Sun rotates the dipolar magnetic field and the corresponding current sheet into an Archimedean spiral structure called the Parker spiral. The interplanetary magnetic field is much stronger than the dipole component of the solar magnetic field. The solar dipole magnetic field of 50-400 Â ° T (in the photosphere) is reduced by an inverted cube from a distance of about 0.1Ã.tT at a distance of Earth. However, according to observations of the spacecraft the interplanetary plane at Earth's location is about 5Ã,TT, about a hundred times larger. The difference is that the magnetic field generated by the electric current in the plasma surrounds the Sun.
Variations in activity
The Sun's magnetic field leads to many effects that are collectively called solar activity. Sun flares and coronal-mass lesions tend to occur in the sunspot group. Slowly change the speed of the solar wind emitted from the coronal hole in the photospheric surface. Both the coronal release-mass and high-speed solar winds bring plasma and magnetic fields between outer space into the Solar System. The effects of solar activity on Earth include the aurora at moderate to high latitudes and disruption of radio communications and electric power. Sun activity is thought to play a major role in the formation and evolution of the Solar System.
By modulation of the solar cycle from the number of sunspots comes modulation corresponding to the weather conditions of space, including those surrounding the Earth where technological systems can be affected.
Long-term changes
Long-term secular changes in the number of sunspots are considered by some scientists, to correlate with long-term changes in solar radiation, which in turn can affect the Earth's long-term climate. For example, in the seventeenth century, the solar cycle seems to have ceased entirely for decades; some sunspots were observed during a period known as the Maunder minimum. It coincided with the era of the Little Ice Age, when Europe experienced a tremendous cold temperature. Previously a longer minima has been found through tree circle analysis and seems to coincide with lower global temperatures than average.
A recent theory claims that there is a magnetic instability in the core of the Sun that causes fluctuations with a period of 41,000 or 100,000 years. This could give a better explanation of the ice age than the Milankovitch cycle.
Phase of life
The sun is currently about half the most stable part of its life. It has not changed dramatically for over four billion years, and will remain stable for more than five billion more. However, once the hydrogen fusion has essentially stopped, the Sun will undergo dramatic changes, both internally and externally.
Formation
The sun formed about 4.6 billion years ago from the collapse of a part of a giant molecular cloud composed largely of hydrogen and helium and which probably gave birth to many other stars. This age is estimated using the computer model of star evolution and via nucleosococcalology. The results are consistent with the radiometric dates of the oldest Solar System material, at 4,567 billion years ago. Ancient meteorite studies reveal traces of stable daughter nuclei from short-lived isotopes, such as the 60-iron, which only form on exploding stars and short-lived stars. This suggests that one or more supernovas must occur near the location where the Sun is formed. The shock waves from nearby supernovae will trigger the formation of the Sun by compressing the material inside the molecular cloud and causing certain areas to collapse under their own gravity. When one fragment of cloud collapses it also begins to spin due to conservation of angular momentum and heats up with increasing pressure. Most of the mass is concentrated in the center, while the rest are flattened into disks that will become planets and other bodies of the Solar System. Gravity and pressure inside the cloud core generate much heat because of the increasing material from the surrounding disk, which eventually triggers nuclear fusion. Thus, the Sun is born.
The main order
The sun is at the center of the main sequence phase, where nuclear fusion reactions in essentially unite hydrogen into helium. Every second, more than four million tons of matter is converted into energy inside the Sun's core, producing neutrinos and solar radiation. At this level, the Sun has converted about 100 times the mass of Earth into energy, about 0.03% of the total mass of the Sun. The sun will spend about 10 billion years as the main sequence star. The sun gradually becomes hotter for the time in the main sequence, since the helium atoms in the nucleus occupy less volume than the united hydrogen atoms. Therefore the core shrinks, allowing the outer layers of the Sun to move closer to the center and experience a stronger force of gravity, according to the inverse square law. This stronger force increases the pressure on the core, which is resisted by a gradual increase in the rate at which fusion occurs. This process accelerates as the nucleus gradually becomes more solid. It is estimated that the Sun has become 30% brighter in the last 4.5 billion years. Currently, the brightness increase is about 1% every 100 million years.
After hydrogen core fatigue
The sun does not have enough mass to explode as a supernova. Instead it will get out of the main sequence in about 5 billion years and start turning into a red giant. As a red giant, the Sun will grow so large that it will swallow Mercury, Venus, and possibly Earth.
Even before it becomes a red giant, the Sun's luminosity will almost double, and the Earth will receive as much sun as Venus has received today. After the hydrogen nucleus runs out in 5.4 billion years, the Sun will expand into a subgiant phase and slowly doubling its size for about half a billion years. It will then grow faster for about half a billion years up to more than two hundred times larger than today and several thousand times more luminous. This then begins the phase of a red-giant branch where the Sun will spend about a billion years and lose about a third of its mass.
After the giant branch of the red-sun the Sun has about 120 million years of active life remaining, but a lot happens. First, the core, full of helium that degenerates fused hard in helium flash, where it is estimated that 6% of the core, itself 40% of the Sun's mass, will be converted to carbon within minutes through the triple-alpha process. The sun then shrank to about 10 times the current size and 50 times the luminosity, with temperatures slightly lower than today. Then it will reach the red clump or horizontal branch, but the star of the Sun mass does not evolve blueward along the horizontal branch. Instead, it only becomes larger and luminous for about 100 million years as it continues to burn helium in its core.
When helium runs out, the Sun will repeat the expansion that followed when the hydrogen in the nucleus has run out, except that this time everything happens faster, and the Sun becomes larger and more radiant. It is a gigantic asymptotic phase, and the Sun alternately burns hydrogen in a shell or helium in a deeper shell. After about 20 million years in the initial asymptotic branch of giants, the Sun becomes increasingly unstable, with rapid mass loss and thermal pulses that increase size and luminosity for several hundred years every 100,000 years or more. The thermal pulse becomes larger each time, with the pulse then pushing the luminosity up to as much as 5,000 times the current level and the radius being more than 1 AU. According to the 2008 model, the Earth's orbit is shrinking due to tidal forces (and, ultimately, dragging from the lower chromosphere), so that it will be swallowed by the Sun near the red giant branch ends, 1 and 3.8 million years after Mercury and Venus respectively -has suffered the same fate. Models vary depending on the level and time of mass loss. Models that have a higher mass loss in red-giant branches produce smaller and less luminous stars at the tip of an asymptotic giant branch, perhaps only 2,000 times luminosity and less than 200 times the radius. For the Sun, four thermal pulses are predicted before it actually loses its outer envelope and starts making planetary nebula. At the end of that phase - it lasts about 500,000 years - the Sun will only have about half of its current mass.
The evolution of post-asymptotic branches-giants is even faster. Luminosity remains approximately constant as the temperature rises, with half released from the Sun's mass becoming ionized into the planet's nebula as an open nucleus of up to 30,000 K. The last naked, white dwarf, will have a temperature of over 100,000 K, and contains about 54, 05% of the Sun's current mass. The planetary nebula will dissolve about 10,000 years, but the white dwarf will survive for trillions of years before fading into a hypothetical black dwarf.
Motion and location
The Sun lies close to the inner edges of the Milky Orion's Arm, in the Local Interstellar Cloud or Gould Belt, at a distance of 7.5-8.5 kpc (25,000-28,000 light-years) from the Galactic Center. The sun is contained in the Local Bubble, a purified hot gas chamber, possibly produced by the remnants of the Geminga supernova, or the double supernovae in the B1 subgroup of the Pleiades moving group. The distance between the local arm and the next arm, Perseus Arm, is about 6,500 light-years away. The Sun, and thus the Solar System, is found in what scientists call the galaxy's habitable zone. The Apex of the Sun's Way, or the sun's peak, is the direction that the Sun travels relative to other nearby stars. This movement goes to a point in the constellation of Hercules, near the star Vega. Of the closest 50 star systems in 17 light years from Earth (the closest is Proxima Centauri's red dwarf in about 4.2 light years), the Sun ranks fourth in mass.
Orbit in Milky Way
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