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Name: Michelle
Status: other
Grade: other
Location: NV
Country: N/A
Date: N/A

How do astronomers measure stellar luminosity?

Dear Michelle,

Astronomers measure a star' luminosity using a scale of magnitudes that has existed for well over a century. Polaris, the north star, is defined as being magnitude 2.0. A star of first magnitude is 2.5 times brighter, and a star of zero magnitude, like VGega, is 2.5 times brighter in turn than a first magnitude star. This way, a fifth magnitude star, faintly visible to the naked eye, is 100 times fainter than a first magnitude star.
Good question! Hope this answer works for you.


David H. Levy

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