It's not from a series, it's based off of a planetarium simulation called Space Engine. The idea behind the wiki is that you find a planet in any old galaxy and create not just a fictional entry for it, but for any species that might reside.
For example, say I find a planet with life orbitting a star. I create a wiki page for the planet (acutual planet name and version of Space Engine included so other users can visit) and write a bit about it, coming up with a fictional history and including physical data and anything unique about the planet I can make up. Then perhaps I create a sentient species for this planet. This goes on another wiki page. Maybe this planet controls a small interstellar government. New page for it. Maybe they have a famous individual. New page. And the list grows. We don't just focus on planets, but on fake species and ideas.
Now seeing as this wiki has grown, I've asked that people follow a canon. There are established governments, species and such. I hope this was a good explanation.
Go to this page. There are different versions, so if you make an article about a planet, just tell us the name of the planet that appears and the version you're using. Each version has a different star seed for procedurally generated planets.