Alien Origins: The Panspermia Hypothesis
Among the most provocative ideas is the panspermia hypothesis, which suggests that life—or at least its essential ingredients-may have arrived on Earth from outer space. Some researchers point to the discovery of amino acids and organic compounds on meteorites as tantalizing evidence that these building blocks exist beyond our planet. While panspermia doesn’t answer how life began, it raises the possibility that Earth’s first organisms may have hitched a ride on comets or space dust.