OUR SUN...!!!

1.Measurements
Our Sun is a normal main-sequence star, one of more than 100 billion stars in our galaxy.
The Sun is by far the largest object in the solar system with a huge diameter of 1,390,000 km and a great mass of 1.989 kg

Trying some simple calculation, you will see more clearly how big our Sun is. It is likely to take you nearly 100 years to walk restlessly around its perimeter, or luckily if you have a good car which provides you a speed of 60 km/h, your ten years will be burnt up by its heat as well (Wow...!)

As it is the closest star to Earth, the Sun is a very important source of heat which sustains life on Earth, and controls our climate and weather.

Conditions at the Sun's core (approximately the inner 25% of its radius) are extreme. The temperature is 15.6 million Kelvin and the pressure is 250 billion atmospheres. At the center of the core the Sun's density is more than 150 times that of water.

3.Huge amount of energy
Nuclear fusion reactions taking place inside the Sun produces a great amount of output energy (about 3.98 megawatts. Each second about 700,000,000 tons of hydrogen are converted to about 695,000,000 tons of helium and 5,000,000 tons of energy in the form of gamma rays. That very huge amount of power travels outwards the sun and is continuously absorbed and re-emitted at lower and lower temperatures. After a long “journey” of from 146 to 152 million km, by the time it reaches the Earth’s surface, it is primarily visible light. For the last 20% of the way to the Earth, this energy is carried more by convection than by radiation.

4.Structure

Photosphere: the surface of the Sun at a temperature of about 5800 K.

Sunspots: "cool" regions at only 3800 K (they look dark only by comparison with the surrounding regions), very large (50,000 km in diameter) and caused by complicated and not very well understood interactions with the Sun's magnetic field.

Chromospheres: a small region lying above the photosphere.

Corona: the highly rarefied region above the chromospheres at the temperatures of over 1,000,000 K. It extends millions of kilometers into space but is visible only during a total solar eclipse.
The Sun's magnetic field is very strong (by terrestrial standards) and very complicated.

5.Solar wind

In addition to heat and light, the Sun also emits a low density stream of charged particles (mostly elecns and protons) known as the solar wind which propagates throughout the solar system at about 450 km/sec. The solar wind and the much higher energy particles ejected by solar flares can have dramatic effects on the Earth ranging from power line surges to radio interference to the beautiful aurora borealis.

The Sun is about 4.5 billion years old. Since its birth it has used up about half of the hydrogen in its core, it will continue to radiate "peacefully" for another 5 billion years or so. But eventually it will run out of hydrogen fuel. It will then be forced into radical changes which will result in the total destruction of the Earth.

So, don’t ever repeat our ancestors’ mistakes in the past which may lead the seemingly “endless” energy of Sun to be “limited”. It must be always a remarkable issue when we are taking advantage of natural resources.