2. Energizing the Sun

Awesome power, enormous times

The Earth intercepts only a modest fraction of the energy being pumped out in all directions from the Sun. When we measure the total amount of sunlight that illuminates and warms our globe, and extrapolate back to the Sun, we find that it is emitting a power of 385.4 million, million, million, million, or 3.854 x 1026, watts. An enormous amount of energy is being expended. In just one second the energy output of the Sun equals the entire energy consumption of the United States for a million years.

The astonishing thing is the Sunís durability; the Sun has managed to last billions of years despite radiating such awesome amounts of energy. In looking back at Earthís history, we find that the Sun has been shining steadily and relentlessly for aeons, with a brilliance that could not be substantially less than it is now. The radioactive clocks in rock fossils indicate, for example, that the Sun was hot enough to sustain primitive creatures on Earth 3.5 billion years ago.

By the early 20th century, when your grandparents might have lived, no one had any clue as to why the Sun, or any other star, could shine so brightly for billions of years. That understanding had to await the discovery of the ingredients of the atom, observations that the Sun is mainly composed of hydrogen, and the realization that sub-atomic energy can be released within the extraordinary conditions inside stars.

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Copyright 2010, Professor Kenneth R. Lang, Tufts University