HISTORY ONLINE

The Sun is the most prominent feature in our solar system. It is the largest object and contains approximately 98% of the total solar system mass. One hundred and nine Earths would be required to fit across the Sun's disk, and its interior could hold over 1.3 million Earths. The Sun's outer visible layer is called the photosphere and has a temperature of 6,000°C (11,000°F). This layer has a mottled appearance due to the turbulent eruptions of energy at the surface.

Solar energy is created deep within the core of the Sun. It is here that the temperature (15,000,000° C; 27,000,000° F) and pressure (340 billion times Earth's air pressure at sea level) is so intense that nuclear reactions take place. This reaction causes four protons or hydrogen nuclei to fuse together to form one alpha particle or helium nucleus. The alpha particle is about .7 percent less massive than the four protons. The difference in mass is expelled as energy and is carried to the surface of the Sun, through a process known as convection, where it is released as light and heat. Energy generated in the Sun's core takes a million years to reach its surface. Every second 700 million tons of hydrogen are converted into helium ashes. In the process 5 million tons of pure energy is released; therefore, as time goes on the Sun is becoming lighter.

The chromosphere is above the photosphere. Solar energy passes through this region on its way out from the center of the Sun. Faculae and flares arise in the chromosphere. Faculae are bright luminous hydrogen clouds which form above regions where sunspots are about to form. Flares are bright filaments of hot gas emerging from sunspot regions. Sunspots are dark depressions on the photosphere with a typical temperature of 4,000°C (7,000°F).

The corona is the outer part of the Sun's atmosphere. It is in this region that prominences appears. Prominences are immense clouds of glowing gas that erupt from the upper chromosphere. The outer region of the corona stretches far into space and consists of particles traveling slowly away from the Sun. The corona can only be seen during total solar eclipses.

The Sun appears to have been active for 4.6 billion years and has enough fuel to go on for another five billion years or so. At the end of its life, the Sun will start to fuse helium into heavier elements and begin to swell up, ultimately growing so large that it will swallow the Earth. After a billion years as a red giant, it will suddenly collapse into a white dwarf -- the final end product of a star like ours. It may take a trillion years to cool off completely.

For the Aztecs, who lived in central Mexico, Tonatiuh was a Sun god. Aztecs believed that four suns had been created in four previous ages, and all of them had died at the end of each cosmic era. Tonatiuh was the fifth sun and the present era is still his. Tonatiuh was in charge of the Aztec Heaven called Tollan. Only dead warriors and women who died in childbirth could be received in Tollan.
Tonatiuh was responsible for supporting the universe. To prevent the end of the world, Aztecs believed it was essential to maintain the strength of the Sun god by offering him human sacrifices.

Amaterasu was the Sun goddess of the oldest Japanese religion called Shinto. When her brother Susanowo treated her badly, she hid in the cave of heaven and closed the entrance with an enormous stone. This made the world dark, and evil spirits came out of their hiding places.
In despair, a conference of the gods decided to trick Amaterasu into coming out by having a party near the cave. They put a big mirror in front of the cave and beautiful jewels on a tree. Uzume, the goddess of laughter, began a dance accompanied by loud music.

Hearing the music and laughter, Amaterasu was so curious that she took a look outside to find out what was going on. She was so fascinated by her own brilliant reflection in the mirror that she came out of the cave. Finally, the light covered and colored the world. Sun also plays important role in european and chinese astrologies.