Cepheid variables

I read a little astronomy and spent most of the night outside stargazing with my binoculars. I was mostly interested in theConstellation Cepheus and the surrounding stars. One star is Delta Cephei a variable star that has a constant change in brightness every five and a third days. This star lends its name to the class of Cepheid variables that were important in determining the size of our galaxy and the distance to the Andromeda Galaxy by Edwin Hubble in 1924 who found cepheids in that galaxy and ended the planetary nebula vs. island universe debate; before Hubble it was believed that these galaxies were where solar systems were being formed in our own Milky Way Galaxy and Hubble showed that the Andromeda Galaxy was two million light years away; I believe Astronomers have refined that to 2.4 million light years. I think I’ll keep an eye on Delta Cephei for the next few night!