NoNukes writes:
My bad. Alpha Centauri is not the closest star. There is an invisible red dwarf star near it that is slightly closer. Still not worth a human visit.
The red dwarf star is Proxima Centauri, which orbits Alpha Centauri - which makes the system trinary rather than binary. There are more likely candidates for planets which could sustain life, such as Epsilon Indi, but they are a bit more than 10 light years away at best.
In the meantime, one could theoretically terraform Mars by altering cometary orbits, shade Venus and create biotech that eats carbon dioxide, or colonize Ganymede and Callisto, just to start, using nuclear power - preferably fusion given how icy they are - for heat and energy.
Small steps first, larger ones are not impossible, just won't happen for awhile.
Read not to contradict and confute, not to believe and take for granted, not to find talk and discourse, but to weigh and consider. - Francis Bacon