There are multiples things to know in order to do this achivement.
> This achievement needs a species that is neither Pacifist nor Xenophile and not fanatic xenophobe (Authoritarian and Materialist is usually a good combo)
> Needs Ironman mode
Step #1First and obviously, you need the Sol system, which must contain a continental world.
> In order to be sure that the system spawn, the easiest way it to spam-create a new galaxy with minimum size, using the "Ring" configuration. If the Sol system is generated, then it will stand outside or inside the ring and will be really visible. If you can't see a system afar far from the ring galaxy, restart.
Step #2Second, you need to have the Human to be in the Machine age.
> For that, send one of your first Corvet right to the system. If there's a spatioport, go back to step #1
> If not, then make several invasion armies (3 are enough) and send a Scientific ship to see in what era they are. If they're Machine age or under, then it's a success. if in the atomic age, then you may restart the game (a bit unsure on atomic age, since WW were right before the opening of atomic age soooooo...).
> If they are at machine age, invade them. If you're successful, then you have your achievement :3
> if they're BEFORE the machine age, then you'll have to use a scientific station in order to bring them here. Once they're at the machine age, stop the enlightement and bring them your democracy.
That's all!
This guide is a quick and efficient way to obtain the achievement, but it can be completed through others means or during one of your casual games