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By Haywood Hunter


There are billions of stars in the sky, with the sun being the closest to Earth among them. It lies at the center of the solar system. For every 27 days, the sun rotates once. It was formed about four and a half billion years ago. It is determined that the sun is at middle of its life, meaning that it shall shine for about 5 billion more years.

The sun's surface is known as the photosphere. Its temperature is about 5,778 K. The sun's core is, however, much hotter, with its temperature being about 15.7 million K. All this energy is produced via nuclear fusion. This is a nuclear reaction where two hydrogen nuclei fuse to form one helium nucleus, accompanied by release of energy.

A distance of 149.6 million kilometers separates the sun and the earth. The sun has a diameter of 1.392 million kilometers and an equatorial circumference of 4.379 million kilometers. These values are 109 times higher than the corresponding earth's measurements. Its surface area is 11,990 times that of earth, measuring 6.0877 trillion kilometer squared. Its volume is 1.3 trillion times that of earth.

The energy from the sun is called solar energy. It is received by the earth through radiation. Since only a fraction of the radiated energy can be absorbed by our planet, a lot of it is reflected back to space. Life on earth depends on the absorbed energy. It is also responsible for our weather, tides and the water cycle.

Through photosynthesis, plants utilize solar energy to make their own food. All other living organisms on earth depend on this food to survive. Energy stored in fossils, as well, result from effects of the sun. This includes coal and petroleum.

Providing unlimited light and heat, the sun is the main source of energy to the earth. Extra applications of solar energy include lighting, generating electricity and in enhancing growth of plants in green houses. Considering all these factors, it is true to say that there can be no life on earth without the sun.

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