Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. The last one will be revealed at the end here. These are the first eight, how do I know, check this post:[url]https://www.bungie.net/en/Forum/Post/183671130/0/0/1[/url] this is a list of what xur says while he's in the tower. He mentions that the traveler has a dark mirror that being the worms here's why. The traveler uses the power of the sky(light) to give the dead, life and infuse them with it's powers. The worms use the power of the deep(dark) to take the living and infuse them with their powers there is your mirror, now then. notice how he mentions he moves base mostly on the planets position (note there is basically your answer there but this gets deeper) Now think why here? why our system? because there is a focal point of some kind of impossible power here and it involves unlocking and correctly matching the nines worlds. (Note: just had a thought this far in, I'm going to need to do an analysis of the planets main composition.) Now lets test your mythology. Everyone know their Norse? So in Norse, there is the tree of life and it connects all the nine realms, earth is at the center. That's all I need to convince me there is some kind of link to great power there. (nine again) So when we get this ninth world and get everything arranged right like xur said we open some kind of portal to some other worlds or allow some kind of power to come flowing through like the power of the tree of life. Now the pat you've been waiting for. that ninth world. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.....and the reef. Yes I know the reef isn't a planet but consider this. The exo stranger mentions that the awoken waver between the light and the dark which is bad for everyone I'm assuming. I'm willing to bet the awoken are the key, much like when we're doing the sword quest we have to make willbreaker's shard and the hadium flakes we start off by making it waver between the light and the dark and once we do we seal it to the light, making the exotic swords. The awoken are the same, right now they are more or less wavering between the light and the dark and we need to seal them to the light to [b]make[/b] the ninth world by using the asteroid belt, combing the fragments to form a world that never was to ultimately give victory to the sky(light) or the deep(dark) . The reef is the ninth world that we have to create by sealing to the light if we are to win the war against the dark. Do you agree? [b]Extended theory[/b]: I learned some things from you guys and now I'm extending with my new knowledge. So I believe the nine are also in a bad state right now as I believe there are only 4 active member (the Jovians) of the nine because they don't want their corrupted sibling Mercury and infected siblings Mars and Venus and the possibly infected sibling earth, to take part in orchestrating the events that will unfold to decide who will seal the ninth world to the light or dark. They want to prevent any bias from either side to assist in that decision so now the nine are helping the light for now (but only to the extent where they will cleanse their siblings from the vex machines inside them) hence the reason why the Joivians are the more important and most mentioned. The nine can be believed to be the cores of the planets as the traveler (in our case) would be the core of the ninth world. meaning the rest of the nine could be similar to the traveler. Edit: I have returned. Edit: forgot Neptune. Here I am trying to be smart. Edit: Changed the title due to some fuss over it.