THE SUN

The sun is the nearest star to us, it is a [Yellow Dwarf star], the Sun is a medium star.

[why we see it the biggest?].

Due to its size and light, some people thought that it is a god, they offers gifts to it.

There was and old Chinese legend which say that a huge dragon eats the sun from time to time.(the eclipse process)

The sun revolve on its axis and around the galaxy. The sun was BORN  from more than 4000 year.

Some people wonders : "How can the sun send all this light and heat to us?"

the Answer is : Huge [NUCLEAR FUSIONS] happens in the core of the Sun.

The symbol of the sun is ..

Time required for the sun to complete ONE rotation around the galaxy is 250 million Earth years!!!

 Diameter of its Equatorial is 1.39 million km .

It gravitational pulling is equal to 28 Earth's gravitational pulling.

When heat generated in the core of the sun, it transfer to its surface then to the space in the form of LIGHT & HEAT.

The time taken by the heat to transfer from its core to its surface is 1000000 years, and it takes 8.5 minutes to transfer from its surface to earth!!

The Sun gives off many kinds of radiation other than light and heat. It also emits radio waves, ultraviolet rays, and X-rays. The Earth's atmosphere protects us from the harmful effects of some of the sun's rays like X-rays, But in nowadays the atmosphere starts to decay, this cause rise in earth's temperature. Ultraviolet rays causes cancer.

The sun rotate on it axis, But not all parts rotate with the same speed. This is called differential rotation.

The sun consists of:

The Sun has several layers: the core, the radiation zone, the convection zone, and the photosphere (which is the surface of the Sun). In addition, there are two layers of gas above the photosphere called the chromosphere and the corona. Events which occur on the Sun include sunspots, solar flares, solar wind, and solar prominences. Sunspots are magnetic storms on the photosphere which appear as dark areas. Sunspots regularly appear and disappear in eleven year cycles. Solar flares are spectacular discharges of magnetic energy from the corona. These discharges send streams of protons and electrons outward into space. Solar flares can interrupt the communications network here on Earth. Solar winds are the result of gas expansion in the corona. This expansion leads to ion formation. These ions are hurled outward from the corona at over 500 kilometers per second. Solar prominences are storms of gas which erupt from the surface in the form of columns which either shoot outward into space or twist and loop back to the Sun's surface.

ADOPTED FROM NASA CD [ STARCHILD : THE SUN ] "CD\docs\starch00\solars00\sun.htm"

SUN PICTURES

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