Cosmologists refer to elements heavier than helium as “metals” and are essential as the building blocks of life, as well as the formation of rocky, terrestrial, Earth-like planets on which life is likely to be found. Widely-accepted cosmological models suggest the early universe was extremely metal-poor, limiting opportunities for life to arise. With the formation of galaxies and on-going stellar synthesis of heavy elements, these opportunities continue to improve. We consider the Galactic Habitable Zone of our Milky Way galaxy, how it may have appeared in the past, and how it may evolve over time, increasing the likelihood of the formation of rocky Earth-like planets, and the opportunities for life to emerge on them.
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