( Jack holding up the white kings started The Reckoning, which if you remember is when meteors start launching towards Skaia. This is why the Lab meteor launched. The defense portals around Skaia are how some of the meteors ended up hitting Earth (like the one that hit Johns house for example)
See this is why I love recaps like this. Because with everything else I have to try and remember from this series, I knew that there was something that might have fallen in the cracks.