We won't be living on alien planets.
We have GOT
to stop this unquestioned narrative
about colonizing Mars, searching for alien planets in the Goldilocks Zone
and all the rest of that nonsense.
None of them will have all of our basic needs as Earth provides, and at best we will have to live in domes or caves under the surface.
Landing in a gravity well is risky and expensive. Launching is even more expensive. There won't be any mining down there for anything but local needs. In fact, planet-dwellers are all-but trapped.
Terra-forming would take thousands of years, and humans just aren't capable of this kind of financial and logistical commitment.
But, we can build perfect homes almost anywhere in the form of orbital colonies. In orbit, where the easy-to reach material is in the first place. In fact, out of the tailings left over from sifting more valuable components out of comets, asteroids and the smaller moons.
Sintered rock powder makes a tough, concrete-like substance. The heat source comes from a reflective mirror. It doesn't even need to be big; a mirror a few feet across can turn sand to glass here on earth. We build up the football or cylinder-shaped habitat like it's inside a gargantuan 3D printer.
We spin it, and establish the ecology of our choice inside, and feed it with power collected from the host star through panels floating nearby.
We'll likely use the Moon for material first, then Mars's moons, then the asteroids. There is material for millions of habitats, each with the population of a county. Before long, the vast majority of Humanity will exist in colonies orbiting the Sun, population exceeding trillions of people.
ANY system that has loose floating material, and a star that is hot or bright enough, without being too irregular, will do.
The galaxy could be teeming with established intelligent life already, perhaps mostly around red dwarfs as they are the most plentiful and live many times longer than Sun-like stars.