Sun: Encyclopedia II - Sun - Human understanding of the Sun

Sun - Human understanding of the Sun

Mankind's most fundamental understanding of the Sun is as the luminous disk in the heavens whose presence above the horizon creates day, and whose absence causes night. In many prehistoric and ancient cultures, the Sun was thought to be a deity or other supernatural phenomenon.

One of the first people in the Western world to offer a scientific explanation for the sun was the Greek philosopher Anaxagoras, who reasoned that it was a giant flaming ball of metal even larger than the Peleponessus, and not the chariot of Helios. For teaching this heresy he was imprisoned by the authorities and sentenced to death (though later released through the intervention of Pericles).

In the early years of the modern scientific era, it was proposed that the Sun extracted its energy from friction of its gas masses, which would yield a Sun no older than a few million years, with a few more million years to go. It was only after Einstein's theory of mass-energy convertibility in the early 20th century that it was finally understood that the sun runs on nuclear fusion and is billions of years old, with several other billion to go.

With respect to the fixed stars, the Sun appears from Earth to revolve once a year along the ecliptic through the zodiac. Thus, the Sun was considered by Greek astronomers to be one of the seven planets (Greek planetes "wanderer"), after which the seven days of the week are named in some languages.

Adapted from the Wikipedia article "Human understanding of the Sun", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki