Sun

::{{otheruses}} For the astrological significance of the Sun, see Solar system in astrology.

General information

The Sun is classified as a main sequence star, which means it is in a state of "hydrostatic balance", neither contracting or 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 http://www.astro.uiuc.edu/~kaler/sow/spectra.html#classes, and the V signifying that it, like most stars, is a "dwarf" star on the main sequencehttp://www.physics.uq.edu.au/people/ross/phys2080/spec/analyz.htm.

Related Topics:
Main sequence - Hydrostatic balance - Nuclear fusion - Hydrogen - Helium - Spectral class - Spectral line

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The Sun has a predicted main sequence lifetime of about 10 billion years. Its current age is thought to be about 4.5 billion years, a figure which is determined using computer models of stellar evolution, and nucleocosmochronology {{ref|Bonanno}}. The Sun orbits the center of the Milky Way galaxy at a distance of about 25,000 to 28,000 light-years from the galactic centre, completing one revolution in about 226 million years. The orbital speed is 217 km/s, equivalent to one light year every 1400 years, and one AU every 8 days.

Related Topics:
Billion - Computer models - Stellar evolution - Nucleocosmochronology - Milky Way - Galaxy - Light-year - Galactic centre - 226 million years - Orbital speed - AU

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The astronomical symbol for the Sun is a circle with a point at its centre (☉).

Related Topics:
Astronomical symbol - Circle with a point at its centre

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