Today, we live in an age of exploration, where robots on Mars and planet-hunting telescopes are beginning to allow us to edge closer to an answer.
While we wait to establish contact, one technique we can use back on Earth is an equation that American astronomer Frank Drake formulated in the 1960s to calculate the number of detectable extraterrestrial civilizations may exist in the Milky Way galaxy.
It is not a rigorous equation, offering a wide range of possible answers. Instead it is more a tool used to help understand how many worlds might be out there and how those estimates change as missions like Kepler, a telescope that is currently searching for Earth-like planets, begin to discover more about our universe.
Until ground-based observations, space telescopes and planet-roving robots uncover any tell-tale signs of life, what better way to speculate on how many intelligent alien civilizations may exist than to explore the universe with our interactive version of the equation.
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