The nearest star to earth and the brightest object in the sky which emits electromagnetic radiation of various wavelengths; some of them harmful to life.

The earth's atmosphere absorbs most of these injurious radiations and life on earth would be impossible with out the heat and light from the sun.

So, it is understandable that as far as life on earth is concerned, people realize that the sun is the most important star in the sky.

The sun's distance from Earth has been calculated as

• Farthest distance: 94,500,000 miles or 152,100,000 kilometers.
• Nearest distance: 91,400,000 miles or 147,100,000 kilometers.
• Average distance: 92,960,000 or 149,600,000 kilometers.

The sun is about 4.6 billion years old and is the dominant body of the solar system, with more than 99% of its mass.

It converts about 4.5 million tons of matter into energy every second by nuclear fusion reactions in its core, producing neutrinos and solar radiation.

The small amount of this energy that penetrates Earth’s atmosphere provides the light and heat that support life.

A sphere of luminous gas 1,392,000 kilometers, or 864,950 miles, in diameter, the Sun has about 330,000 times the mass of Earth.

Its core temperature is close to 15,000,000 Kelvins, 27,000,000 °Fahrenheit, and its surface temperature is about 6,000 Kelvins, 10,000 °Fahrenheit.

The Sun god who brings life-giving heat and light to Earth unit.

The amount of power density in sunlight received at the earth's surface at noon on a clear day (about 1,000 Watts/square meter).

The equivalent number of hours per day when solar irradiance averages 1,000 w/m2; for example, six peak sun hours means that the energy received during total daylight hours equals the energy that would have been received had the irradiance for six hours been 1,000 w/m2.