Life as we know it requires biogenic elements, a source of energy, liquid water, and a suitable, reasonably stable environment for evolution to take place. Even extremophile bacteria, which live in, and are adapted to, diverse temperatures, pressures, and chemical conditions, need organic ingredients, energy, and water. Astronomer Carl Sagan suggested that it is “carbon chauvinism” to assert that carbon-based life is the only possible form that life might take. Nevertheless, the search for life beyond Earth mostly focuses on looking for places with conditions similar to those on our home planet and organisms with biologies similar to our own.
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