When we observe the stars in the night sky, their brightness can be pretty dramatic, but the way astronomers measure brightness is not how one might intuitively think about it. In astronomy ...

Its immense brightness is why its name ... expand and cast off the outer layers of this star. Vega lies in the constellation Lyra, having an apparent visual magnitude of 0.03.

The brighter the star is overall, the longer the period ... in 1912 -- in a chart of 25 cepheid periods and their apparent brightness. Using this, astronomers only needed to know the period ...