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CONTENT - A description of our Sun which is both studies in terms of its internal structure and the miscellaneous energetic events he triggers
 

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Sun Like a Structure Sun Like an Active Body

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The Sun is certainly the most perfect sphere, like an object, in the solar system, due to its intense gravity, with an oblateness of a mere 8.01 milli-arcseconds in excess in terms of apparent diameter. The years of high solar activity however are turning the Sun oblate somewhat due to 'supergranules' -large convection cells- emerging near the Sun's equator and adding a width of 10.77 milli-arcseconds to the Sun's apparent diameter. Sun has a layered structure

->Everything In and On the Sun Linked to the Inner Dynamo!
Massive currents of electrically-charged gas (plasma) circulate in patterns in the inner layers of the Sun, which yield the solar dynamo, which in turn gives to the Sun's powerful magnetic field. Almost all solar activity from sunspots to solar flares is regulated by that inner dynamo, as the only way to appreciate how it works is to use the 'heliosismology' consisting into monitoring the waves created by the inner motions of the Sun and coming to 'ring' against the surface. The Sun's complex magnetic field is mostly made up of closed loops of magnetic field with both ends anchored in the Sun. The Sun's less-common open field lines migrate between the Sun's north and south poles over the course of the 11-year solar cycle, during which the overall magnetic field reverses in polarity. The solar magnetic field plays a vital role in dictating the structure of the Sun's atmosphere, and acts as a conduit for mass and energy to flow into the solar corona and solar wind

->The Solar Magnetic Field Makes a Difference at the Solar Poles The ESA-NASA Ulysses spacecraft found again -like in 1995-1996- that there is a difference of a 7 to 8 percent in temperature between a cooler north pole and a warmer south one, with a difference in temperature of the order of 80,000° F(44,000° C). It seems related to the structure of the magnetic field as that difference has followed the 11-year cycle of the flip of both solar magnetic poles. That's of importance as the solar wind emanates from the solar poles
The Ulysses saw another tricky observation, as a solar storm which emerged from a sunspot region at the equator was funneled in such a way that the craft was hit as it was overflying the south pole, as the solar wind emanates from the Sun's poles. That flow from the poles in terms of the solar wind may have the latter spill down to the Sun's equator, or to be confined to the mid-latitudes only

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->How Solar Science Evolved
As astronomer Thomas Harriot first saw sunspots through a telescope in 1610, the study of the Sun really took off about 130 years ago following Dutch astronomer Pieter Zeeman’s discovery that a magnetic field, or a field of force generated by electrical currents, alters some spectral lines. Within a decade, American astronomer George Ellery Hale used Zeeman’s discovery to demonstrate that sunspots contained strong magnetic fields. After World War II, when there was a growing recognition of solar activity’s influences on radio frequency propagation in Earth’s upper atmosphere. Scientists used leftover German rockets to soar above Earth’s atmosphere to measure emission in wavelength ranges absorbed by atmospheric gases, and found that the Sun's ultraviolet radiation varied wildly from year to year. Such rocket missions were limited however to five to 10 minutes in duration. With the space age, NASA developed spacecraft called the Orbiting Solar Observatories (OSOs) to study solar activity, with eight spacecraft launched between March 1962-June 1975, making solar science over a complete solar cycle of 11 years. The concept of space weather was found in 1946 by U.S. physicist Scott Forbush when he detected incoming energetic particles spiking not long after a solar flare. Coronal mass ejections, as far as they are concerned, had been predicted in the 1960's and they were first observed by December 1971 from a orbiting space observatory. As soon as by 1859, English astronomer Richard Carrington made a link between a rare solar white flare, and northern lights seen down to the island of Cuba, or telegraph failure (that was called the Carrington Event). Helioseismology also came in the early 1960's, discovering global oscillations (or pressure waves) occurring at the solar surface and helping to probe solar interior as scientists suspected for a while sound waves to also heat the corona. On Skylab, launched by 1973, astronauts operated a battery of telescopes to learn more about variability of the extreme ultraviolet and X-ray emission from the corona as their mission unfortunately showed that a human-operated telescope wasn’t very effective as they nearly always missed the beginning of flares. In 1980s the Solar Maximum Mission improved upon by using automated flare detection to digitally coordinate all the instruments to direct to the flare within a fraction of a second as such early missions laid the groundwork for missions like SOHO. NASA-ESA SOHO studied the internal structure of the Sun, its outer atmosphere and the origin of solar wind. When SOHO was launched on Dec. 2, 1995, the field of heliophysics was still lacking knowledge about those elements. At the time, it was thought that solar flares were the primary Earth-effective solar event, in part because they were the most commonly-observed as SOHO's coronograph allowed to CMEs, a major piece of the space weather puzzle, and much more common—and more variable. SOHO had the Sun seen like a dynamic object as the satellite provided the basis for more than 5,000 scientific papers and yielded the recognition that we live in the extended atmosphere of a magnetically active star. Solar missions, on a other hand, like NASA’s Solar Dynamics Observatory (SDO), NASA’s Solar and Terrestrial Relations Observatory, and NASA’s Interface Region Imaging Spectrograph, or JAXA/NASA’s Hinode have been shaped by SOHO's discoveries. NASA currently flies, for example, multiple spacecraft about the Sun, providing a range of different observations. Astronomers also are using background low frequency sounds of the Sun to study it, from solar flares to coronal mass ejections, or the layers of the Sun

Far from the still, whitish-yellow disk it appears to be from the ground, Sun sports, in the non-visible wavelengths, a dynamic surface and exterior, with twisting, towering loops and swirling cyclones that reach into the solar upper atmosphere. Sun indeed is a giant magnetic star, made of material that moves in concert with the laws of electromagnetism. Scientists are not sure exactly where in the Sun the magnetic field is created. It could be close to the solar surface or deep inside the Sun or over a wide range of depths. As the Sun is made of plasma, a gas-like state of matter in which electrons and ions have separated, creating a super-hot mix of charged particles, when charged particles move, they naturally create magnetic fields, which in turn have an additional effect on how the particles move. The plasma in the Sun, therefore, sets up a complicated system of cause and effect in which plasma flows inside the Sun churned up by the enormous heat produced by nuclear fusion at the center, create the Sun's magnetic fields, a system known as the solar dynamo. Magnetic fields are revealed through loops and towers of material in the corona as footprints on the Sun’s surface, or photosphere, of these magnetic loops can be more precisely measured using an instrument called a magnetograph, which measures the strength and direction of magnetic fields. The solar magnetic system is known to drive the approximately-11-year solar activity cycle as, with every eruption, the sun’s magnetic field smooths out slightly until it reaches its simplest state. After that minimum, the Sun’s magnetic field grows more complicated over time until a new peak. At solar maximum, the magnetic field has a very complicated shape with lots of small structures throughout which are the active regions we see. At solar minimum, the field is weaker and concentrated at the poles, a very smooth structure that doesn’t form sunspots. A comparison, in terms of the relative complexity of the solar magnetic field between January 2011 and July 2014 is showing that, by January 2011, three years after solar minimum, the field is still relatively simple, with open field lines concentrated near the poles. At solar maximum, in July 2014, the structure is much more complex, with closed and open field lines poking out all over – ideal conditions for solar explosions. Rossby waves also exist on the Sun, those waves linked to any rotating fluid, which likely are a link between surface's fluid motion and magnetic fields. They could help scientists to better predict the formation of sunspots and the eruption of solar flares. Hot, bright features called brightpoints in the Sun’s corona can be used to track the roiling motions of material deeper in the solar atmosphere and they are linked to increased magnetic activity. Solar Rossby waves flow under the surface and are thought to drive space weather as brightpoints may serve as a clue, linking how the solar cycle leads to increased numbers of solar flares every 11 years. Rossby waves couple activity happening on instantaneous timescales with things that are happening on decadal and longer timescales. Flares and coronal mass ejections that may appear random are probably governed at some level

->Do the Major Sun-Earth Interactions Occur when Both the Solar and the Earth Magnetic Field Have a Same Polarity?
One thought until now that the major interactions between the solar events and the Earth's magnetosphere did occur when both the Earth's magnetic field and the Sun's one featured an opposite polarity. Recent data, in 2008, by NASA's Themis mission are showing that it might well be the opposite which occurs! The most important breaches into the Earth's magnetosphere might occur when the Earth's magnetic field and the Sun's one have a same polarity. That would constitute a major discovery!

->Flares, CMEs, Proton Storms, Geomagnetic Storms
Taken together, flares, CMEs, and solar energetic particles constitute space weather. The most usual mechanism of a solar event is that a flare explodes from the magnetic field lying over a region of sunspots, unleashing visible light and X-rays. This translates into a Coronal Mass Ejection (CME), with a large amount of solar material expelled into the interplanetary space. CMEs hold charged protons, electrons and heavy ions. As the CME moves, taking some days to reach Earth, it plows through the 'usual' solar wind, accelerating protons to high energies and pushing them ahead. Such particles are termed 'solar energetic particles' (SEPs) as they thus are streams of very fast protons. CMEs may be interspersed into the solar wind like denser clouds of solar wind material. The proton storm then hits Earth, as the CME too, trigerring auroras and bringing potentially harmful radiation to spacecraft and astronauts. Even a particularly fast stream of solar wind may reach so. Mastering the 'solar weather' is of importance for the satellites in orbit around Earth as it will be more important still for the renewed presence of man at Moon, and further to Mars. Astronomers now mostly do not separate flares and CMEs anymore as they better say 'Solar Eruptive Events' instead as a same burst of energy creates both kind of events with part of the energy shooting into the sky and turning a CME and part of the material driven down to the Sun's surface and appearing as the flare. The magnetic field lines on which energetic particles from a flare travel curve from the Sun to Earth unlike CMEs, which travel in straight lines. Energetic particles were magnetically connected to Earth even though, for example, the associated CME may miss us. Such protons thus are reaching Earth much more quickly than the CME as it even happens that they hit a CME preceding them and create a shock wave there. Solar flares and other energetic events from the Sun are also producing gamma rays by accelerating charged particles, which collide and interact with Sun's atmosphere and surface. The area on the right side of the solar disk, generally, has a almost direct magnetic connection to Earth as the Sun's magnetic field lines curve as they extend away from the sun in conjunction with Sun's rotation. NASA stated by late 2015, that a 12 percent chance of a giant solar flare is extant in the next 10 years, able to bring global, EMP-type damages on Earth. A geomagnetic storm is fast-moving material coming from the Sun -either high-speed solar wind streams, or CMEs- colliding with Earth's magnetic field and sending it oscillating

->More About Flares and CMEs!
Two main types of explosions occur on the Sun: solar flares and coronal mass ejections. Coronal mass ejections and solar flares are, at our Sun, a expression of the reconnection phenomenon, like the one seen in the Earth's magnetosphere, a process which can affect plasma, or space filled with electrically charged particles and electric and magnetic fields. Unlike the energy and X-rays produced in a solar flare -which can reach Earth at the speed of light in eight minutes and be constituted originally with light, energy and X-rays- coronal mass ejections are giant clouds of solar material that take one to three days to reach Earth. The strongest flares are almost always correlated with CMEs. A dramatic magnetic power struggle at the Sun’s surface determine whether a flare is followed by a CME. A magnetic cage prevents the growing of a twisted magnetic rope associated with the onset of a CME. The rope however may be sufficiently strong to trigger a flare. Both eruptions are created when the motion of the Sun’s interior contorts its own magnetic fields. Like the sudden release of a twisted rubber band, the magnetic fields explosively realign, driving vast amounts of energy into space. That constitutes a kind of magnetic reconnection. Strong electric fields are generated that produce a large force on charged particles and, in the ionized gas of the Sun’s atmosphere, this process sends electrons and ions flying at speeds approaching the speed of light, causing them to release high-energy gamma rays. This phenomenon can create a sudden flash of light, or a solar flare. Flares can last minutes to hours (particles accelerated by a CME on the far side of the Sun somehow may reach around to produce a gamma-ray glow on the side of the Sun facing Earth). Some of the energy released in the flare also accelerates very high energy particles that can reach Earth in tens of minutes. The flare is like the muzzle flash, which can be seen anywhere in the vicinity. The CME is like the cannonball, propelled forward. Traveling over a million miles per hour, the hot material of CMEs called plasma takes up to three days to reach Earth. The differences between the two types of explosions can be seen through solar telescopes, with flares appearing as a bright light and CMEs appearing as enormous fans of gas swelling into space. Solar energetic particles (SEPs) are the streams of high-speed particles blasted from the Sun from narrow flares or wide coronal mass ejections (CMEs). A SEP event typically occurs every couple weeks. The young Sun was more active than nowadays frequently -perhaps even daily- blasting out intense bursts of radiation. As both flares and CMEs can yield disturbances at Earth under the form of radio ones, or magnetic ones respectively, a fleet of NASA heliophysics observatories in space are always on the watch for these explosions as the U.S. NOAA’s Space Weather Prediction Center runs simulations and can make predictions about when a CME will arrive at Earth, then alert appropriate groups

The Sun is an active body. Magnetic fields emerging from below the surface of the Sun are the essential factor to solar events. The Sun is expelling, through various, usual or unusual events, a flurry of elements and radiation into the solar system. Latest studies might hint to that even small solar events are affecting large regions of our Sun through the dispersion of magnetic instabilities and waves. Solar radiation storms, those bursts of incredibly fast-moving protons and electrons resulting from solar events are solar-accelerated particles can get up to 80 percent of the speed of light. The Sun is working on a 11-year cycle that is that each 5-6 years the activity of the Sun is reaching a peak, as 5-6 years later, it's reaching a low. Generally, it may be considered that it's the sunspots which are at the origin of solar flares, coronal mass ejections, and an intense UV radiation. A 2003 study is showing further that the most unusual and energetic solar events, the Coronal Mass Ejections (CMEs) are related to a cleansing of the Sun's magnetic field. CMEs are increasing at the moment of the peak of the 11-year cycle as does their speed (during last peak, there were more than a thousand CMEs at the Sun). CMEs do not peak however until 2 years after the solar peak. During about the same duration, the solar magnetic field is reverted, that is the North pole of the dipole become the South pole and reciprocally. During these two years, CMEs are polar, occurring at one pole, then at the other two years later. 'Solar braiding,' or energy transfer from Sun's magnetic field to corona is showing how the evolution of the field explain Sun's working and any events like flares. At less of 1 percent of the solar system's mass, the whole of the planets in the solar system, look like they have a influence, in terms of their configurations translates into gravitational effects, on the solar acticity as a whole as they modify the circulation of plasmas, hence the solar global magnetic field and the activity of the Sun along a solar cycle

All the various sorts of the solar outflow are interacting with the planets of the solar system, especially with Earth. Planets are protected from the solar wind, particles, and radiation by a magnetosphere, which is a tear drop-shaped magnetic field extending on the far side of the planet. The most known interaction between the solar events and the planetary media are the auroras. Some solar particles are managing to reach the poles of the planets, where they are making the atoms in the upper atmosphere glow. Auroras, at the Earth, are usually occuring from 60 miles (96 km) to several hundred miles (several hundred km) high, as some may occur to more than 500 miles. Most recent studies, generally, are showing that there are far more short-term changes in solar activites than previously thought

->Another Feature of Sun?
A study of the Sun by the Japanese craft Hinode has spotted that powerful X-ray jets are expelled from the solar surface hundreds times a day, propeling American continent-sized blobs of hot gas at speeds of 2 million miles per hour (3.2 million km/h). Such jets were already known, as the new craft allowed to see that they are occurring at an important pace of about 240 daily. They are not linked to any place of the surface, occurring about anywhere there. It looks like they are triggered by reconnection events similar, albeit much smaller, than those which power the solar flares, at about a thousand times less than a typical M-class flare. They are scaled-down filamanets. Those X-ray jets might well represent up to between 10 and 25 percent of the input of the Sun into the solar wind. The X-ray jets might too provide for the heating of the corona which remained unclear until now, by throwing there 'Alfven waves' which crack there like a whip and heat the gas

->More for the Solar Wind from The Margins of the Active Regions!
As the solar wind usually considered forming in the solar active regions (the regions of the solar sunspots), it might that those flux be perturbed -and accelerated up to speeds of 150,000 mph (240,000 km/h), with temperatures between 1 and 3 millions degrees Celsius- from a still badly known activity at the margins of those regions. Such a contribution might be an important one to the total volume of the solar wind, with the equivalent of billions tons a day by an active region!

->Flares and CMEs
A flare is a high-power energy release per unit time, a mostly radiative energy release event , and the most powerful storm in our solar system, as A CME is a lower power event occurring over a much longer time period, although carrying lots of mechanical (kinetic) and magnetic (potential) energy. CMEs blast out over a billion of tons of particles at millions of miles per hour. Solar electrons and ions accelerated up to near the speed of light affect all Sun’s atmospheric layers and pass through the corona, which may add some also. Post coronal loops can be seen coiled over the area where a flare occurred, lingering during about one Earth's day. Sometimes the process which leads to a flare and a CME is contradicted when one mass of magnetized material, instead of colliding with another one, just encounter a invisible boundary called a 'hyperbolic flux tube.' A hyperbolic flux tube is the result of a collision of two bipolar regions, a magnetic complex structure of four alternating and opposing magnetic fields ripe for magnetic reconnection. The tube may, for example, reconnect a filament’s magnetic field lines with those of the ambient Sun. Regular pulses disturbances -- akin to earthquakes -- are rippling through the chromosphere during a flare as they are later observed like oscillations in the corona

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