What is stellar magnitude?
Stellar magnitude is number indicating the luminosity of a star or object.
about 2000 years back Hipparchus classified stars from 1 to 6.
number 1 for the brightest stars and no 6 for the most faint visible to naked eye.
After modern instruments came into service the scale extended to minus for very bright stars,Sun and moon.
For every number change in magnitude the brightness changes about 2..5. When number increases stars are less bright.
In this system Sun is -26.7 Moon=-12.6 Venus 4.4 Sirius -1.4