The Sun  - Next Planet - Back to Planet Walk
Photos Courtesy NASA
    The Sun, at the center of our Solar System, is at the beginning of this scale model of the Solar System. In this model, the Sun is represented as a ball 4 inches in diameter. This makes the scale of our model 1 inch = 180,000 miles. Each step that you take (28 inches) is then 5.0 million miles.

    Our Sun is a huge, massive, spherically shaped object, containing about 99.8% of all the matter in our Solar System. (The planet Jupiter contains most of the remaining material.) The sun has a mass of 1.9891x1030 kg = 4.384x1030 lb = 2.192x1027 tons, or a mass 333,000 times that of the Earth. The radius of the Sun is 696,265,000 meters = 696,265 km =  432,639 mi or a radius 109 times that of the Earth. The volume of the Sun is so huge that it could hold over 1 million Earths.

    The Sun is a typical star, and is also the star that is nearest to the Earth. It is composed of a mixture of 73% hydrogen, 25% helium, and 2% other elements by weight. The nuclear fusion reactions that produce the sun's energy are converting hydrogen into helium, changing the relative amount of these two elements present in the Sun. In each nuclear conversion 4 hydrogen atoms are combined to produce a helium atom. This reaction occurs throughout the Sun and by this process our Sun converts 600 million tons of hydrogen into 596 million tons of helium every second. The missing 4 million tons of matter are converted to energy, according to Einstein's equation E=mc2. This amount of energy is so large that the Sun gives off 40,000 watts of light from every square inch of its surface. (Compare this to the 60 and 100 watt light bulbs we use in our homes.) As far as we know, the Sun has been giving off this energy steadily for the last four and one half billion years, and will continue to do so for several billion years more. Only half a billionth of this energy reaches the Earth. The rest is radiated out into space.
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This and all photos in this web site are courtesy NASA.