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Name: Junqiang S.
Status: N/A
Age: 40s
Location: N/A
Country: N/A
Date: 2000-2001

Although the Sun is a giant ball, it is equivalent to a bright circlar disk when it is viewed from the Earth. Do you know the distribution of the brightness on the disk for a given wavelength or could you tell me where I find the information? Thanks.

Junqiang :

I agree that the sun looks like a disk when viewed from earth, but I would think that it could be treated as a point source in terms of light reaching the earth's surface. By "brightness on the disk for a given wavelength", I assume you mean intensity as a function of wavelength. My understanding is that the distribution of energy as a function of wavelength (or frequency) is that of a black-body radiator with a temperature of 6000 degrees Kelvin. Some further discussion on this can be found in a book called "The Refrigerator and the Universe: Understanding the Laws of Energy" by Martin Goldstein.

Good luck,
Jim Rubin

Do a web search using the phrase: "solar spectrum" using the search engine: . You will find many "hits" with great graphics. The solar spectrum consists roughly of a black body with thousands of fine absorption lines due to elements in the cooler upper atmosphere of the Sun.

Vince Calder

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