What is the magnitude of Algol?
The magnitudes of stars are measured on an inverse logarithmic scale, so a star of magnitude 3 is ten times dimmer than a star of magnitude 2 and 100 times dimmer than a star of magnitude 1. Algol has a magnitude of 2.12 and decreases by 1.28 during the primary eclipse and decreases by only 0.07 during the secondary eclipse.