Multiplayer in No Man's Sky has been a big question surrounding the game, and it is an issue Hello Games has skirted around. While they've maintained the game isn't multiplayer focused at all, the best answer they've given is that essentially, you wouldn't be able to meet your friends in universe because it is so big.

Well, that has already been disproven on launch day of the game. As reported by Kotaku, when player TheSadCactus landed on a planet that had clearly already been visted, he tried to meet up with the original explorer. The was Psytokat, and the two tried to coordinate on the planet to see what happens when there are two players in the same place at the same time.

As it turns out, not much happened. While both players seemd to be in exactly the same place at the same time, they couldn't see each other. They also tried this in several near by locations to no avail.

Of course, that doesn't mean there is no interaction. The planet seemed to retain all the names saved by another player, even if ther was no direct interaction.

While this is more or less what I expected would happen, it still doesn't help the Hello Games were so obtuse about explaining what would happen in the game if you did try to meet up with someone else. That's a shame, because I expect the developer will get a lot of flack for this, despite it essentially not being a common thing in the game at all.