STELLAR MAGNITUDE. (1)
The record of the positions of stars in a catalog called esteleares lists is a fundamental baseline for important astronomical knowledge such as the determination of the time, the phenomena of precession and nutation, proper motion of stars. The earliest catalog was developed by astronomer Greek Hipparchus in 127 BC It contained the positions of 1080 stars divided into six classes according to their apparent brightness Arabs kept another catalog of stars called "Almagest" of Ptolemy, in this work we have inherited the custom to group the stars brightness classes or magnitudes. The classes of brightness were called magnitude, calling for the brightest of 1 st magnitude, 2 nd, 3 rd, 4 th, etc., until the 6 th magnitude, the latter are the faintest stars that distinguish somple view.
For magnitude means the apparent brightness of stars we see and dimensions of these stars.
In 1856 the astronomer Norman Pogson established the "Pogson scale" means a 1st magnitude star has an apparent brightness 2,512 times greater than a 2 nd magnitude star, this 2,512 light intensity greater than a 3 rd magnitude and so on. Pogson included the star Aldebaran and Altair to the base times the scale. These magnitude scales extending one hand toward zero and negative numbers, to encompass the brightest stars like the Sun and the Moon.
The apparent magnitude depends on the brightness of the star and the distance that is an example, Sirius has an apparent magnitude of -1.46 (the most brilliant of heaven, is to 9 light years away, while that Rigel is 2000 times more luminous, with a magnitude appears to be 0.08 at a distance 100 times greater).
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