We're going back to Vega.
Vega is the brightest star in the constellation of Lyra and you can see the magnitude scale down here.
We defined that Vega was 0 magnitude and you can see its size matches that magnitude.
That's how it works.
Okay, we know there are some limitations of this.
Some of the limitations include human eyes.
They are more sensitive to red and yellow light than blue light.
