Could Cepheid Variables Help Measure the Hubble Constant?

💡 The Answer

• By measuring distances to galaxies with Cepheids, Hubble's law reveals expansion rate.
• Edwin Hubble himself used Cepheids in the Andromeda Galaxy to prove it was separate.
• Modern observations of Cepheids in Type Ia supernova host galaxies refine H₀.
• Tensions between Cepheid-based H₀ and cosmic microwave background values hint at new physics.