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Sun
Rays |
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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 , and the
V signifying that it, like most stars, is a "dwarf" star
on the main sequence.
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 . 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. |
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