The dataset consisting of 22 galaxies, which Edwin Hubble utilized in 1929 to formulate the Law of Cosmic Expansion, played a pivotal role in understanding cosmic structure. These observations were conducted through the Hooker Telescope at the Mount Wilson Observatory, enabling Hubble to measure the distances and recession velocities of these galaxies. Notably, Hubble identified spiral nebulae, now recognized as independent galaxies, breaking with the earlier conception that all nebulae were part of the Milky Way.
The dataset includes crucial information such as recession velocities (v), solar velocity discounts (vₛ), proper distances (r), apparent magnitudes (m), and absolute magnitudes (M). Analysis of these parameters revealed a clear trend: galaxies farther away tend to recede more rapidly, providing crucial observational evidence for the expansion of the universe. Conclusions drawn from these pioneering measurements by Hubble were essential in constructing modern cosmology and solidified the idea of a dynamic, expanding universe.