Sun - Photosphere

(332,950 Earths) (27.9 g) The Sun (or Sol) is the star at the center of our Solar system. Earth orbits the Sun, as do many other bodies, including other planets, asteroids, meteoroids, comets and dust. Its heat and light support almost all life on Earth. The Sun is a ball of plasma with a mass of about 2×1030 kg, which is somewhat higher than that of an average star. About 74% of its mass is hydrogen, with 25% helium and the rest made up of trace quantities of heavier elements. It is thou ...

Including:

• Sun - General information
• Sun - Structure
• Sun - Core
• Sun - Radiation zone
• Sun - Convection zone
• Sun - Photosphere
• Sun - Temperature minimum
• Sun - Chromosphere
• Sun - Corona
• Sun - Theoretical problems
• Sun - Solar neutrino problem
• Sun - Coronal heating problem
• Sun - Faint young sun problem
• Sun - Magnetic field
• Sun - Position of the Sun through the year
• Sun - Solar space missions
• Sun - History and future of the Sun
• Sun - Human understanding of the Sun
• Sun - The Sun as a power source
• Sun - Sun and eye damage

Read more here: » Sun: Encyclopedia - Sun

The Sun is a near-perfect sphere, with an oblateness estimated at about 9 millionths, which means the polar diameter differs from the equatorial by about 10 km. This is because the centrifugal effect of the Sun's slow rotation is 18 million times weaker than its surface gravity (at the equator). Tidal effects from the planets do not significantly affect the shape of the Sun, although the Sun itself orbits the center of mass of the solar system, which is offset from the Sun's center mostly because of the large mass of Jupiter. The mass of the Sun is so comparatively great that the center of mass of the solar system is generally wit ...

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Sun, Sun - General information, Sun - Structure, Sun - Core, Sun - Radiation zone, Sun - Convection zone, Sun - Photosphere, Sun - Temperature minimum, Sun - Chromosphere, Sun - Corona, Sun - Theoretical problems, Sun - Solar neutrino problem, Sun - Coronal heating problem, Sun - Faint young sun problem, Sun - Magnetic field, Sun - Position of the Sun through the year, Sun - Solar space missions, Sun - History and future of the Sun, Sun - Human understanding of the Sun, Sun - The Sun as a power source, Sun - Sun and eye damage

Read more here: » Sun: Encyclopedia II - Sun - Structure

Mankind's most fundamental understanding of the Sun is as the luminous disk in the heavens whose presence above the horizon creates day, and whose absence causes night. In many prehistoric and ancient cultures, the Sun was thought to be a deity or other supernatural phenomenon. One of the first people in the Western world to offer a scientific explanation for the sun was the Greek philosopher Anaxagoras, who reasoned that it was a giant flaming ball of metal even larger than the Peleponessus, and not the chariot of Helios. For teaching this heresy he was imprisoned b ...

See also:

Sun, Sun - General information, Sun - Structure, Sun - Core, Sun - Radiation zone, Sun - Convection zone, Sun - Photosphere, Sun - Temperature minimum, Sun - Chromosphere, Sun - Corona, Sun - Theoretical problems, Sun - Solar neutrino problem, Sun - Coronal heating problem, Sun - Faint young sun problem, Sun - Magnetic field, Sun - Position of the Sun through the year, Sun - Solar space missions, Sun - History and future of the Sun, Sun - Human understanding of the Sun, Sun - The Sun as a power source, Sun - Sun and eye damage

Read more here: » Sun: Encyclopedia II - Sun - Human understanding of the Sun

The Sun is classified as a main sequence star, which means it is in a state of "hydrostatic balance", neither contracting nor expanding, and is generating its energy through nuclear fusion of hydrogen nuclei into helium. The Sun has a spectral class of G2V, with the G2 meaning that its color is yellow and its spectrum contains spectral lines of ionized and neutral metals as well as very weak hydrogen lines [3], and the V signifying that it, like ...

See also:

Sun, Sun - General information, Sun - Structure, Sun - Core, Sun - Radiation zone, Sun - Convection zone, Sun - Photosphere, Sun - Temperature minimum, Sun - Chromosphere, Sun - Corona, Sun - Theoretical problems, Sun - Solar neutrino problem, Sun - Coronal heating problem, Sun - Faint young sun problem, Sun - Magnetic field, Sun - Position of the Sun through the year, Sun - Solar space missions, Sun - History and future of the Sun, Sun - Human understanding of the Sun, Sun - The Sun as a power source, Sun - Sun and eye damage

Read more here: » Sun: Encyclopedia II - Sun - General information

The Sun is thought to be a second-generation star, whose formation may have been triggered by shockwaves from a nearby supernova. This is suggested by a high abundance of heavy elements such as iron, gold and uranium in the solar system: the most plausible ways that these elements could be produced are by endothermic nuclear reactions during a supernova or by transmutation via neutron absorption inside a massive first generation star. Our Sun does not have enough mass to explode as a supernova, and its mass is below the Chandrasekhar ...

See also:

Sun, Sun - General information, Sun - Structure, Sun - Core, Sun - Radiation zone, Sun - Convection zone, Sun - Photosphere, Sun - Temperature minimum, Sun - Chromosphere, Sun - Corona, Sun - Theoretical problems, Sun - Solar neutrino problem, Sun - Coronal heating problem, Sun - Faint young sun problem, Sun - Magnetic field, Sun - Position of the Sun through the year, Sun - Solar space missions, Sun - History and future of the Sun, Sun - Human understanding of the Sun, Sun - The Sun as a power source, Sun - Sun and eye damage

Read more here: » Sun: Encyclopedia II - Sun - History and future of the Sun

All matter in the Sun is in the form of gas and plasma due to its high temperatures. This makes it possible for the Sun to rotate faster at its equator (about 25 days) than it does at higher latitudes (28 days near its poles). The differential rotation of the Sun's latitudes causes its magnetic field lines to become twisted together over time, causing magnetic field loops to erupt from the Sun's surface and trigger the formation of the Sun's dramatic sunspots and solar prominences. (See magnetic reconnection). The solar activity cycle includ ...

See also:

Sun, Sun - General information, Sun - Structure, Sun - Core, Sun - Radiation zone, Sun - Convection zone, Sun - Photosphere, Sun - Temperature minimum, Sun - Chromosphere, Sun - Corona, Sun - Theoretical problems, Sun - Solar neutrino problem, Sun - Coronal heating problem, Sun - Faint young sun problem, Sun - Magnetic field, Sun - Position of the Sun through the year, Sun - Solar space missions, Sun - History and future of the Sun, Sun - Human understanding of the Sun, Sun - The Sun as a power source, Sun - Sun and eye damage

Read more here: » Sun: Encyclopedia II - Sun - Magnetic field

The Sun is classified as a main sequence star, which means it is in a state of "hydrostatic balance", neither contracting nor expanding, and is generating its energy through nuclear fusion of hydrogen nuclei into helium. The Sun has a spectral class of G2V, with the G2 meaning that its color is yellow and its spectrum contains spectral lines of ionized and neutral metals as well as very weak hydrogen lines [3], and the V signifying that it, like most stars, ...

See also:

Sun, Sun - General information, Sun - Structure, Sun - Core, Sun - Radiation zone, Sun - Convection zone, Sun - Photosphere, Sun - Temperature minimum, Sun - Chromosphere, Sun - Corona, Sun - Theoretical problems, Sun - Solar neutrino problem, Sun - Coronal heating problem, Sun - Faint young sun problem, Sun - Magnetic field, Sun - Position of the Sun through the year, Sun - Solar space missions, Sun - History and future of the Sun, Sun - Human understanding of the Sun, Sun - The Sun as a power source, Sun - Sun and eye damage

Read more here: » Sun: Encyclopedia II - Sun - General information

Sun - Solar neutrino problem. For some time it was thought that the number of neutrinos produced by the nuclear reactions in the Sun was only a third of the number predicted by theory, a result that was termed the solar neutrino problem. Several neutrino observatories were constructed, including the Sudbury Neutrino Observatory and Kamiokande to try to measure the solar neutrino flux. It has recently been found that neutrinos have rest mass, and can therefore transform into harder-to-detect varieties of neutrinos ...

See also:

Sun, Sun - General information, Sun - Structure, Sun - Core, Sun - Radiation zone, Sun - Convection zone, Sun - Photosphere, Sun - Temperature minimum, Sun - Chromosphere, Sun - Corona, Sun - Theoretical problems, Sun - Solar neutrino problem, Sun - Coronal heating problem, Sun - Faint young sun problem, Sun - Magnetic field, Sun - Position of the Sun through the year, Sun - Solar space missions, Sun - History and future of the Sun, Sun - Human understanding of the Sun, Sun - The Sun as a power source, Sun - Sun and eye damage

Read more here: » Sun: Encyclopedia II - Sun - Theoretical problems

To obtain an uninterrupted view of the Sun, the European Space Agency and NASA cooperatively launched the Solar and Heliospheric Observatory (SOHO) on December 2, 1995. Originally a two-year mission, SOHO is now over ten years old (as of late 2005). It has proved so useful that a follow-on mission, the Solar Dynamics Observatory, is planned for launch in 2008. Elemental abundances in the photosphere are well known from spectroscopic studies, but the composition of the interior of the Sun is much less well known. A solar wind sample re ...

See also:

Sun, Sun - General information, Sun - Structure, Sun - Core, Sun - Radiation zone, Sun - Convection zone, Sun - Photosphere, Sun - Temperature minimum, Sun - Chromosphere, Sun - Corona, Sun - Theoretical problems, Sun - Solar neutrino problem, Sun - Coronal heating problem, Sun - Faint young sun problem, Sun - Magnetic field, Sun - Position of the Sun through the year, Sun - Solar space missions, Sun - History and future of the Sun, Sun - Human understanding of the Sun, Sun - The Sun as a power source, Sun - Sun and eye damage

Read more here: » Sun: Encyclopedia II - Sun - Solar space missions