The Drake Equation, named for astronomer Frank Drake, is a complex formula that provides a rough estimate for the odds of finding other forms of life in the universe. More recently, NASA scientists have used the Drake Equation to determine that the odds that Earth is the only planet with life are 1 in 10 billion trillion, according to NASA.
Now here’s the catch: Many of these exoplanets are thousands of light years away. That means if we do find signs of life, we can’t be sure that whatever organism we’re seeing is still alive. Worse, communicating directly with a far-off life form is impossible because of the time difference. In the case of the closest star to our system — Proxmia Centauri — the lag is 4.2 light-years. Proxima Centauri also hosts an Earth-like planet.