|de la Catardiere, Philippe. "The Sun." Larousse Astronomy. New York: Larousse, 1986: 84.||"The pressure of the sun is equal to 340 billion times the earth's atmospheric pressure."||3.4 × 1011 atm|
|Gwynn, Robert P. and Norton, Peter B. Macropedia: Knowledge in Depth. Robert McHenry Ed. San Francisco: Encyclopedia Britannica, 1993: 456, 387.||"The central pressure of the sun is at least 10,000 times greater than that at the center of the earth, which is 3,500 kilobars."||3.5 × 1011 atm|
|McFarlon, Donald. Guiness Book Of World Records. 27 ed. New York: Sterling Publishing, 1989: 100.||"The sun has a core pressure of 1.65 × 109 tons/in sq."||2.25 × 1011 atm|
|Asimov, Isaac. The Collapsing Universe. New York: Isaac Asimov, 1977: 52.||"The pressure at the center of the sun is equal to 100,000,000,000 atmospheres."||1.0 × 1011 atm|
|"Astronomy & Space Science." The New Book of Popular Science. New York: Grolier, 1996: 81.||"There's pressure at the center of the sun of more than 1 million metric tons/cm sq."||9.9 × 108 atm|
The sun is our closest star. It gives off massive amounts of energy. It is the center of the solar system and we rely on it for survival. The mass of the sun is enormous and is pressing inward on the core. In order for the sun to withhold that pressure it needs to return the same amount. If it does not push out at the same amount of pressure it will collapse and fall in.
The sun is able to maintain it's size due to the intense heat within the sun's core which produces pressure that balances out the two forces. The sun is composed of mostly helium and hydrogen. What happens is that the hydrogen nuclei collide into one another and form helium nuclei. This process of transformation from hydrogen to helium is called the proton-proton chain. In order for the sun to keep the pressure within, it has to give off energy by the process of the proton-proton chain. It fuses and converts 1.0 × 109 kg/s of hydrogen nuclei into helium nuclei.
The pressure at the center of the sun ranges from 3.4 × 108 atm to 2.25 × 1011 atm depending upon the source. Some sources don't give numbers, but only compare it to the earth's characteristics.
Marina Treybick -- 1997