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# Sun

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The sun is the solitary star of our solar system, sometimes called Sol. The planet Earth and all of her sister planets, both the other terrestrial planets and the gas giants, orbit the sun in accordance with Newtons Laws of Gravity.

The sun is the nearest star to Earth and the brightest object in the sky.

Other bodies that orbit? the sun include asteroids, meteoroid?s, comets, [trans-neptunian object]?s, and, of course, dust?.

The sun is a main sequence star, with [spectral class]? G2, meaning that it is somewhat bigger and hotter than the average star but far smaller than the largest [red giant]? star. A G2 star has a main sequence lifetime of about 10 billion years, and the sun has probably about 5 billion, as determined by nucleocosmochronology?. One outstanding question about the sun is the difference between the number of neutrinos observed from the sun, and the number predicted by theory, the solar neutrino problem.

Other characteristics of the sun are:

Radius | 696000 km
Volume | 1,41 1018 km2
Mass | 1,9891 1030 kg
Relative mass | 333,400 Earth's masses
Density | 1,41 g cm3
Central density | 150 g cm3
Supreficial gravity | 274 m s2
Temperature | 5780 K
Period of rotation | 27 d 06 h 36 m
Mean distance from Earth | 150,000,000 km
Apparent magnitude | -27
Absolute magnitude | 4.8

Observation of the sun discloses such phenomena as : (it is crucial to know that direct observation can cause permament sight loss)

- Sunspots
- faculae?
- [Solar flare]?s
- [Solar prominence]?s
  - quiescent prominences
  - eruptive prominences

Other terms related to the sun :

- [Solar wind]?
- Photoshere?
- Chromosphere?
- Corona?
- [Aurora borealis]?
- [Aurora australis]?
- Airglow?

See also: sun mythology

/Talk?

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Last edited August 3, 2001 12:07 pm (diff)
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