Cepheid variables articles
What did Edwin Hubble's measurement of the Andromeda Nebula definitively prove?
What specific type of pulsating star did Hubble rely on to gauge the distance to M31?
What fundamental law established by Henrietta Swan Leavitt links Cepheid period to brightness?
What powerful ground-based telescope did Hubble use at Mount Wilson Observatory for his measurements?
What was Hubble's initial calculated distance to Andromeda around 1924-1925?
What term describes a Cepheid variable used because its true luminosity (absolute magnitude) is known?
What two magnitudes must be compared to calculate the distance using the difference in brightness?
By establishing Andromeda as external, by what approximate factor did Hubble's measurement expand the known universe?
What fundamental system of measurement relies on the Cepheid variable technique as its first rung?
What technical difficulty did Hubble overcome when observing variable stars within M31?