Knowledge upgrade about the Sun

Our Sun

The sun at the heart of our solar system is a yellow dwarf star, a hot ball of glowing gases. Its gravity holds the solar system together, keeping everything from the biggest planets to the smallest particles of debris in its orbit. Electric currents in the sun generate a magnetic field that is carried out through the solar system by the solar wind — a stream of electrically charged gas blowing outward from the sun in all directions.
 With a radius of 432,168.6 miles (695,508 kilometers), our sun is not an especially large star — many are several times bigger — but it is still far more massive than our home planet: 332,946 Earths match the mass of the sun. The sun's volume would need 1.3 million Earths to fill it.

The core of the Sun extends from the center to about 20–25% of the solar radius.It has a density of up to 150 g/cm3(about 150 times the density of water) and a temperature of close to 15.7 million kelvins (K).By contrast, the Sun's surface temperature is approximately 5,800 K.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.Fusing four free protons (hydrogen nuclei) into a single alpha particle (helium nucleus) releases around 0.7% of the fused mass as energy,so the Sun releases energy at the mass–energy conversion rate of 4.26 million metric tons per second (which requires 600 metric megatons of hydrogen), for 384.6 yottawatts (3.846×1026 W), or 9.192×1010 megatons of TNT per second. Theoretical models of the Sun's interior indicate a power density of approximately 276.5 W/m3.In radiation zone (from the core out to about 0.7 solar radii) thermal radiation is the primary means of energy transfer. The temperature drops from approximately 7 million to 2 million kelvins with increasing distance from the core.
The Sun's convection zone extends from 0.7 solar radii (200,000 km) to near the surface. In this layer, the solar plasma is not dense enough or hot enough to transfer the heat energy of the interior outward via radiation.The visible surface of the Sun, the photosphere, is the layer below which the Sun becomes opaque to visible light. Above the photosphere visible sunlight is free to propagate into space, and almost all of its energy escapes the Sun entirely. The change in opacity is due to the decreasing amount of H− ions, which absorb visible light easily.The outermost layer is the coolest layer of the Sun is a temperature minimum region extending to about 500 km above the photosphere, and has a temperature of about 4,100 K.
 The sun's magnetic field is carried out through the solar system by the solar wind — a stream of electrically charged gas blowing outward from the sun in all directions. Since the sun rotates, the magnetic field spins out into a large rotating spiral, known as the Parker spiral.Approximately every 11 years, the sun's geographic poles change their magnetic polarity. When this happens, the sun's photosphere, chromosphere and corona undergo changes from quiet and calm to violently active. The height of the sun's activity, known as solar maximum, is a time of solar storms: sunspots, solar flares and coronal mass ejections. These are caused by irregularities in the sun's magnetic field and can release huge amounts of energy and particles, some of which reach us here on Earth. This space weather can damage satellites, corrode pipelines and affect power grids.
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