After a cursory read of the article, I'm not sure the title is doing the article any favors here. From my read, it sounds like

a. This is about comet orbitals of the solar system

b. There appear to be _at least two_ planes of comet orbitals that are not co-planar with the planetary plane (both at roughly 60 degrees from the planetary plane)

c. One of these orbitals was initially empty (the article calls this the "empty orbital")

d. Over time, solar- (and galactic-?) tides filled the empty orbital

I think there is a lot here, but, again, cursory read.