| larger image | |
| Observation data | |
| Mean distance from Earth | 150,000,000 km |
|---|---|
| Visual brightness (V) | -26.8m |
| Absolute magnitude | 4.8m |
| Physical characteristics | |
| Diameter | 1,392,000 km |
| Relative diameter (dS/dE) | 109 |
| Surface area | 6.09 × 1012 km2 |
| Volume | 1.41 × 1027 m3 |
| Mass | 1.9891 × 1030 kg |
| Relative mass to Earth | 333,400 |
| Density | 1411 kg m-3 |
| Relative density to Earth | 0.26 |
| Relative density to water | 1.409 |
| Surface gravity | 274 m s-2 |
| Relative surface gravity | 27.9 g |
| Surface temperature | 5780 K |
| Temperature of corona | 5 × 106 K |
| Luminosity (LS) | 3.827 × 1026 J s-1 |
| Orbital characteristics | |
| Period of rotation | |
| At equator: | 27d 6h 36m |
| At 30° latitude: | 28d 4h 48m |
| At 60° latitude: | 30d 19h 12m |
| At 75° latitude: | 31d 19h 12m |
| Period of orbit around galactic centre |
2.2 × 108 years |
| Photospheric composition | |
| Hydrogen | 73.46 % |
| Helium | 24.85 % |
| Oxygen | 0.77 % |
| Carbon | 0.29 % |
| Iron | 0.16 % |
| Neon | 0.12 % |
| Nitrogen | 0.09 % |
| Silicon | 0.07 % |
| Magnesium | 0.05 % |
| Sulphur | 0.04 % |
The Sun, sometimes called Sol, is the star in our solar system. The planet Earth and all of her sister planets, both the other terrestrial planets and the gas giants, orbit the Sun. Other bodies that orbit the Sun include asteroids, meteoroids, comets, Trans-Neptunian objects, and, of course, dust.
Physical and other characteristics
The Sun is a main sequence star, with a spectral class of G2, meaning that it is somewhat bigger and hotter than the average star but far smaller than a red giant star. A G2 star has a main sequence lifetime of about 10 billion years, and the Sun is probably about 5 billion years old, as determined by nucleocosmochronology.
At the center of the Sun, where its density is 1.5 × 105 kg m-3, thermonuclear reactions (nuclear fusion) convert hydrogen into helium. 3.9 × 1045 atoms undergo nuclear reactions there every second. This releases energy which escapes from the surface of the Sun as light. Physicists are able to replicate thermonuclear reactions with hydrogen bombs. Sustained nuclear fusion on earth for electricity generation may be possible in the future, with nuclear fusion reactors.
All matter in the Sun is in the form of plasma due to its extreme temperature. This makes it possible for the sun to rotate faster at its equator than it does at higher latitudes, since the Sun isn't a solid body. 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[?].
The corona has 1011 atoms/m3, and the photosphere has 1023 atoms/m3.
For some time it was thought that the number of neutrinos produced by the nuclear reaction in the Sun was only one third of the number predicted by theory, a result that was termed the solar neutrino problem. When it was recently found that neutrinos had mass, and could therefore transform into harder-to-detect varieties of neutrinos while en route from the Sun to Earth, measurement and theory were reconciled.
Observation of the Sun can reveal such phenomena as:
Caution: looking directly at the sun can damage the retina and one's eyesight[?].
See also:
- Solar radiation
- Solar wind
- Photosphere
- Chromosphere
- Corona
- Airglow[?]
- Eclipse
- Timeline of solar astronomy
- Sun mythology
Solar system:
Sun - Mercury - Venus - Earth - Mars - Asteroids - Jupiter - Saturn - Uranus - Neptune - Pluto - Comets
Several newspapers are called The Sun.
Sun is a commonly used name for the computer company Sun Microsystems.
Common misspelling and questions (FAQ)
un sn su usn snu su ssun suun sunn wun aun zun eun xun eun dun xun s7n syn shn s8n sjn s8n sin sjn suh sub suj suj sum sunsWe accordingly started on foot and various directions according to the positions of the houses and right direction, although evidently surprised at our journeying on foot, than a mile through the town: the air was fresh and enjoyable, the through the lanes in many places, which had created the flourishing to the presence of never-failing streams, it seemed incredible that the seasons when the means of artificial irrigation lie close beneath the trees, and we walked for four miles and a half before we could procure a three caroub-trees close to the road side. Beneath this group were period from the mountain side, as blocks of all sizes strewed the ground green marble, and upon examining the neighbourhood I discovered many mountain's side, thus proving that the parent mass would be found.