Part 6/11:
Over decades, astronomers have employed two primary methods to measure the Hubble Constant: local, late-universe observations (redshift-based measurements) and early-universe estimates derived from the CMB. These approaches have yielded conflicting values.
Late-Universe Measurements
Using methods like Cepheid and Mira variable stars, supernova observations, and megamaser galaxies, astronomers have refined the Hubble Constant to approximately 73.5 km/sec per megaparsec. These measurements look at the current universe, observing how galaxies are moving away from us now. Recent studies, such as those utilizing Type-Ia supernovae and water vapor megamasers, reinforce this higher estimate.