For centuries, scientists have speculated about the existence of life beyond Earth. The discovery of exoplanets in the habitable zone of other stars has fueled these theories, suggesting that microbial life may exist on planets or moons elsewhere in the universe. The search for alien life also extends to moons like Europa and Enceladus, where subsurface oceans could harbor life.
In addition to microbial life, some theories propose the existence of intelligent extraterrestrial civilizations, and programs like SETI (Search for Extraterrestrial Intelligence) attempt to detect signals from distant civilizations. While no direct evidence of alien life has been found, the quest to discover whether we are alone in the universe continues.