what is brightness of stars?
In fact, the true brightness of Polaris is ten thousand Suns. When stating the true brightness, or luminosity, of stars, it is convenient to compare them with the luminosity of our own Sun. Our sun shines with a power output of 4 x 1026 Watts; for convenience, we say that this amount of power equals one Sun. A star that has only half the power output of the Sun is said to have a luminosity of 1/2. Another measure of a stars brightness is called its magnitude. The larger the number, the fainter the star. The brightest stars are about magnitude zero, and the faintest stars that can be seen with the naked eye are about magnitude 5.