Sun

The Sun, shining above the ocean.

The sun, as viewed by a satellite.

The Sun is the star around which the Earth, and the whole solar system turns. Viewed from the Earth, the Sun appears as a circle of light in the sky. The rotation of the Earth around itself makes the Sun seems to turn around the Earth. The Sun rises in the East, and sets in the West.

When the Sun rises, it is day, and when it sets, it is night.

Most of the energy forms which exist on Earth, exist or work due to the Sun.

History

The sun was born five billion years ago. The best explanation for how it came to exist is the "nebular hypothesis". This assumes that the universe already existed (so it's after the big bang). A large cloud of dust and gas, spinning around, slowly started to get tighter and tighter around the sun, and most of what settled near the sun became our solar system; the planets with the sun at the centre, the stars, the other minor planets, comets, and then, asteroids.

The structure of the Sun

The Sun has a very precise structure to it:

From inner to outer:

• Nucleus
• Radioactive zone
• Convective zone
• Solar atmosphere, with photosphere, chromosphere and solar crown.

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