Sun

                                             Sun (Sol)
The Sun, sometimes
called Sol, is the star             [Image of the Sun from SOHO]
in our solar system. The                    larger image
planet Earth and all of                   Observation data
her sister planets, both
the other terrestrial    Mean distance from Earth  150,000,000 km
planets and the gas      Visual brightness (V)     -26.8m
giants, orbit the Sun.
Other bodies that orbit  Absolute magnitude        4.8m
the Sun include                       Physical characteristics
asteroids, meteoroids,
comets, Trans-Neptunian  Diameter                  1,392,000 km
objects, and, of course, Relative diameter (dS/dE) 109
dust.
                         Surface area              6.09 × 1012 km2
Physical and other
characteristics          Volume                    1.41 × 1027 m3

                         Mass                      1.9891 × 1030 kg
The Sun is a main
sequence star, with a    Relative mass to Earth    333,400
spectral class of G2,    Density                   1411 kg m-3
meaning that it is
somewhat bigger and      Relative density to Earth 0.26
hotter than the average  Relative density to water 1.409
star but far smaller
than a red giant star. A Surface gravity           274 m s-2
G2 star has a main       Relative surface gravity  27.9 g
sequence lifetime of     Surface temperature       5780 K
about 10 billion years,
and the Sun is probably  Temperature of corona     5 × 106 K
about 5 billion years    Luminosity (LS)           3.827 × 1026 J s-1
old, as determined by
nucleocosmochronology.                Orbital characteristics
                         Period of rotation        Ê
At the center of the
Sun, where its density                 At equator: 27d 6h 36m
is 1.5 × 105 kg             At 30¡ latitude: 28d 4h 48m
m-3, thermonuclear                At 60¡ latitude: 30d 19h 12m
reactions (nuclear                At 75¡ latitude: 31d 19h 12m
fusion) convert hydrogen
into helium. 3.9 ×    Period of orbit around 2.2 × 108 years
1045 atoms undergo                 galactic centre
nuclear reactions there               Photospheric composition
every second. This       Hydrogen                  73.46 %
releases energy which
escapes from the surface Helium                    24.85 %
of the Sun as light.     Oxygen                    0.77 %
Physicists are able to   Carbon                    0.29 %
replicate thermonuclear
reactions with hydrogen  Iron                      0.16 %
bombs. Sustained nuclear Neon                      0.12 %
fusion on earth for
electricity generation   Nitrogen                  0.09 %
may be possible in the   Silicon                   0.07 %
future, with nuclear     Magnesium                 0.05 %
fusion reactors.
                         Sulphur                   0.04 %
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 is not 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.

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.

Observation of the Sun can reveal such phenomena as:

   * Sunspots
   * Faculae
   * Solar flares
   * Solar prominences
        o quiescent prominences
        o eruptive prominences
   * Coronal mass ejection

Caution: Looking directly at the sun can
damage the retina and one's eyesight.

The astronomical symbol for the sun is the circumpunct.

How to - Physics - History - Companies - Internet - Video Games - List of Phobias - September 11, 2001
Radio - Timelines - Chemistry - Genealogy - Family - Film - SARS - Cancer - Medicine - DVD - Calendar
Countries - Disease - Health Science - Dentistry - Economics - AIDS - Law - Autism - Statistics - Bible
Recipes - Architecture - Computers - History of the Internet - Personal computer - Apple Macintosh
War - Presidents of the United States - United States Constitution - Universe - Philosophy - Animals
Biology - United States Constitution - Marketing Topics - Sports - Television - History of Computing

Debt Help - Free Credit Report - Mortgages - Loans - Cheap Flights