Page 7 - Curriculum Visions Dynamic Book

Phenomenal energy from hydrogen
Deep in the interior of any star the temperature is high enough (10,000,000°C) and the density great enough (30 g/cu cm, ten times the density of rocks on the Earth’s surface) for a nuclear fusion reaction to occur.
Stars have a central core composed of helium (made from hydrogen), surrounded by a shell where hydrogen is converted to new helium, and an outer shell composed mostly of hydrogen (which will eventually be used as fuel). This outer shell determines the life of the star. When all of its fuel is used up, the star will die.
fuel: a concentrated form of chemical energy. The main sources of fuels (called fossil fuels because they were formed by geological processes) are coal, crude oil and natural gas. Products include methane, propane and gasoline. The fuel for stars and space vehicles is hydrogen.
fusion: combining atoms to form a heavier atom.
radiation: the exchange of energy with the surroundings through the transmission of waves or particles of energy. Radiation is a form of energy transfer that can happen through space; no intervening medium is required (as would be the case for conduction and convection).
thermonuclear reactions: reactions that occur within atoms due to fusion, releasing an immensely concentrated amount of energy.
An endless supply of cheap energy
Scientists know that if they can use fusion to make energy they can use hydrogen from ordinary water (in a form called heavy water). This supply will last for billions of years.
The main problem is that, because
a nuclear reactor can only be a tiny fraction of the size of a star, the size (and gravity) must be compensated for by creating even higher temperatures than exist in stars. This is what scientists are working on today and why it may take to the middle of next century to achieve it.
Also...
In the inner region of a star four hydrogen atoms are converted into one helium atom. During this process about one-third of the mass is lost and converted into energy.
Einstein’s famous equation E = mc2, where E is energy, m is mass and c is the velocity of light, shows that when mass
is lost it is converted into phenomenal amounts of energy. A nuclear reaction inside a star delivers energy from hydrogen 60 million times more effectively than chemical reactions such as the burning
of hydrogen in oxygen. The Sun converts 600 million tonnes of hydrogen each second, creating 400 million tonnes of helium. Part of this energy occurs as visible light rays, accounting for the brightly glowing ball that we see as the Sun.
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