The Sun is the spectral type G2V yellow star at the center of our
solar system. The Earth as well as many other bodies (including other
planets, asteroids, meteoroids, comets and dust) orbit the Sun, and it
accounts for more than 99% of the solar system's mass. Different
latitudes of the Sun rotate at different rates; a point on the equator
takes 25 days, while a point at a pole takes 36 days. The resultant
torsion upsets the Sun's very strong magnetic field to create an
11-year solar cycle of activity. Heat and light from the Sun have
supported almost all life on Earth. Humans use sunlight to grow crops
(see photosynthesis) and power solar cells. The Sun is a ball of
plasma with a diameter of 1.392 million km (864,950 mi) and a mass of
about 2.0 x 10^30 kg, which is somewhat higher than that of an average
star. About 74% of its mass is hydrogen, with 25% helium, and the rest
made up of trace quantities of heavier elements. The Sun is about 4.6
billion years old, and is about halfway through its main sequence
evolution, during which nuclear fusion reactions in its core fuse
hydrogen into helium.
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Today's selected anniversaries:
The Dutch East India Company was established.
Uncle Tom's Cabin, a novel by Harriet Beecher Stowe about slavery in
the United States before the Civil War, was first published.
The Paris Convention for the Protection of Industrial Property, one of
the first intellectual property treaties, was signed.
The antiretroviral drug AZT became the first antiviral medication
approved for use against HIV and AIDS.
The Aum Shinrikyo sect carried out a poison gas attack on the Tokyo
subway system, killing 12 people and injuring more than 6,000 with
Wikiquote of the day:
"The spirit of truth and the spirit of freedom — these are the
pillars of society." -- Henrik Ibsen