The Physics
Factbook
An encyclopedia of scientific essays

# Power of the Sun

Bibliographic Entry Result
(w/surrounding text)
Standardized
Result
Heimler, Neal. Principles of Science. New York: Merrill, 1979. "temperature surface: 6000 °C" 4.1 × 1026 W
SPARTAN 201-3: The Sun. Solar Data Analysis Center. NASA Goddard Space Flight Center. "… surface temperature is less than 6000 K" 4.1 × 1026 W
Compton's Interactive Encyclopedia. CD-ROM. 1996. "The sun has a surface temperature of 5800 K" 3.6 × 1026 W
Muirden, James. Stars and Planets. Kingfisher, 1993. "… outer layer of sun is 5800 K" 3.6 × 1026 W
"Sun." World Book Encyclopedia. Field Enterprises, 1970. "… about 126 trillion horsepower is sent to earth" 4.7 × 1025 W
"BNSG 133, Sun."Bill Nye The Science Guy. PBS. 20 November 1998. "Four-hundred septillion watts! That's 400 trillion-trillion watts!" 4 × 1026 W

The sun is a large body in space that is 150 million kilometers away from earth. The sun's energy makes life possible on earth. The heat from the sun creates weather and winds. Its energy can be used to run machines yet most of the sun's energy is lost in space. The Earth only receives about one two-billionth of the sun's total energy. Some people don't believe this because the sun seems so hot in the summer. According to the World Book Encyclopedia, "about 126 trillion horsepower is sent to earth."Dividing the converted value of 9.4 × 1016 watts by 2 × 10−9 gives a total power of 4.7 × 1025 watts.

The sun's interior has a temperature of 14 to 15 million kelvin and its surface about 6000 kelvin. The radius of the sun is about 700,000 kilometers. To determine the power of the sun, scientists use the Stefan-Boltzmann Law

Where

• is the Stefan-Boltzmann constant,
• T is surface temperature, and
• is the surface area.

e.g.,

The power value for the sun is very large and small changes in the values plugged into the formula will make big changes in the result. That is why this value isn't exact. There are many variables that can effect the result and these variables change, scientists have no choice but to make an approximated value for the power of the sun.

Matthew Tsang -- 1999

Bibliographic Entry Result
(w/surrounding text)
Standardized
Result
Larson, Richard B. & Volker Bromm. "The Universe's First Stars." Scientific American. December 2001: 70. "Luminosity: 3.85 × 1023 kilowatts" 3.85 × 1026 W

Editor's Supplement -- 2001