I just finished Lost and the Damned from the Space Marine Battles series. This may end up containing spoilers...

What the heck are we to make of "Keeler's Comet"?

The whole story is structured around the "periodic Keeler's Comet". On one hand, it's just a plot device, but at the same time, this is fandom and there are no mere plot devices. We must explain EVERYTHING.

So this is a "Comet" that travels between systems on an orbit around something which is never made clear(seems like it must be the galactic center). Further, its orbit is apparently on 10,000 year period. But, it is on an orbit which since last time it was observed took it through the Eye of Terror.

The initial descriptions make it sound like a purely natural occurrence and nothing in the story contradicts this other than to say it got warped in passing through the Eye.

Clearly, it's moving at LEAST at a high fraction of light speed, and in fact may be moving even FTL.It sounds like anything but a natural occurrence to begin with. Is there any other explanation? Did I miss some bit of explanation/exposition?