Using the period of bright stars and the standard candle formula you can measure distances to galaxies at the edge of the universe.

Question

Quizplus · Accepted Answer

The period-luminosity relationship of bright stars, such as Cepheid variables, is indeed used to measure distances, but it is effective only for relatively nearby galaxies (up to about 100 million light-years away). For galaxies at the edge of the universe, astronomers use other methods, such as Type Ia supernovae or redshift measurements, which are applicable over much larger distances.

Using the Period of Bright Stars and the Standard Candle