Scientists have now discovered a few thousand planets orbiting other stars and, based on these observations, believe there may be as many as 8.8 billion potentially habitable Earth-sized planets in the Milky Way alone. Include stars smaller than the sun and that number increases to 40 billion potentially habitable Earth-like planets.
Some take these observations as an indicator we couldn’t possibly be the only technologically advanced civilization in existence—others wonder why we haven’t heard from... read more