In the long list of Earth-like planets we’ve discovered, we’ve found one that’s really, really, Earth-like. “Proxima B” as it is currently known orbits Proxima Centauri, the 2nd closest star to us (first closest being the sun). It has the conditions needed to support life, and it’s close enough that we could go there one day.
This new world is slightly larger than Earth and does a full orbit of its sun every 11 days, due to being much closer to its star, which itself is much cooler than ours. Despite that rather stark difference, the planet is otherwise extremely similar to Earth. It boasts a climate temperate enough to support liquid water, and may well house alien life.
That is pure conjecture for now, as we have no way of observing the planet’s surface in enough detail to know either way. One argument against the possibility of life is that its atmosphere contains far more ultraviolet radiation than our own, meaning any life would have to be well-hardened against such a thing to exist. Still, if the turians of Mass Effect can do it, I’m sure any potential critters on Proxima B can.
However, unlike with other Earth-like planets we’ve discovered, the exact nature of Proxima B need not be relegated to theory and debate. At only 4 lightyears away we could get pelting probes at it right now and have some solid info in a few generations’ time. If the prognosis looks good then the wealthy among us could jet off on a multi-generational shuttle so that their great-great grandchildren can seed life across the world. While the rest of us burn on the toxic wasteland the Earth will inevitably become.