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Name: janette l gubala
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Date: 1993 - 1999

How bright do stars shine?

The brightness of stars as seen from the Earth is called "apparent visual magnitude"; it is designinated by "m subscript v" and is a logarithmic scale like the Richter scale used for earthquakes. The brightest star seen from the Earth's northern hemisphere is Sirius, the Dog Star with a _m subscript v_ of -1.5 (the stellar magnitude scale is one in which a negative number is brighter than a positive number).

The absolute visual magnitude, designated by "M subscript v", gives the true brightness:

Deneb (alpha Cygnus) has Mv = -6.9, and Rigel (beta Orion) is almost as bright with Mv = -6.8.

On the absolute scale, Sirius is only Mv = +1.4; it *appears* to be the brightest because of its nearby distance, only 2.65 parsecs.


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