About the Book
Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Pages: 217. Chapters: Sun, Fluorescent lamp, Astrophysical X-ray source, Aurora (astronomy), X-ray astronomy, Ball lightning, Plasma (physics), Corona, History of X-ray astronomy, Double layer (plasma), Polywell, Energetic neutral atom, Solar flare, Ionosphere, Heliosphere, Microplasma, Pinch (plasma physics), Variable Specific Impulse Magnetoplasma Rocket, High Frequency Active Auroral Research Program, Langmuir probe, Magnetohydrodynamics, MHD generator, List of plasma (physics) articles, Diffusion damping, Strangeness production, Fusor, Spheromak, Birkeland current, Corona discharge, X-ray astronomy detector, Dense plasma focus, Bremsstrahlung, Plasma stability, Quark-gluon plasma, Ferrofluid, QCD matter, Induction plasma technology, Electrothermal instability, Adiabatic invariant, Magnetic reconnection, Paschen's law, High-power impulse magnetron sputtering, Dynamo theory, Negative temperature, Coronal loop, Plasma stealth, Electrostatic discharge, Plasma scaling, Debye length, Plasma acceleration, Plasmon, Critical ionization velocity, Vlasov equation. Excerpt: The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields. It has a diameter of about 1,392,684 km, about 109 times that of Earth, and its mass (about 210 kilograms, 330,000 times that of Earth) accounts for about 99.86% of the total mass of the Solar System. Chemically, about three quarters of the Sun's mass consists of hydrogen, while the rest is mostly helium. The remainder (1.69%, which nonetheless equals 5,628 times the mass of Earth) consists of heavier elements, including oxygen, carbon, neon and iron, among others. The Sun formed about 4.6 billion years ago from the gravitational collapse of a region within a large molecular cloud. Most of the matter gathered in the center, while the rest flattened into an orbiting disk that would become the Solar System. The central mass became increasingly hot and dense, eventually initiating thermonuclear fusion in its core. It is thought that almost all other stars form by this process. The Sun's stellar classification, based on spectral class, is G2V, and is informally designated as a yellow dwarf, because its visible radiation is most intense in the yellow-green portion of the spectrum and although its color is white, from the surface of the Earth it may appear yellow because of atmospheric scattering of blue light. In the spectral class label, G2 indicates its surface temperature of approximately 5778 K (5505 C), and V indicates that the Sun, like most stars, is a main-sequence star, and thus generates its energy by nuclear fusion of hydrogen nuclei into helium. In its core, the Sun fuses 620 million metric tons of hydrogen each second. Once regarded by astronomers as a small and relatively insignificant star, the Sun is now thought to be brighter than about 85% of the stars in the Milky Way galaxy, most of which are red dwarfs. The absolute magnitude of the Sun is +4.83; however, as the star closest to Earth, the Sun is the brig
