Quote:

caused the Earth to wobble on its axis


Um, no. This may look like a big event to a seismologist, but compared to the angular momentum of the Earth this won't even qualify as noise. Too little mass involved, far too little change in moment arm.

The annual random variation in rotation, caused by whatever is going in the core, will swamp this.

FYI - rough estimates now suggest 2004 MN probably won't be naked-eye visible after all. So no spectacle. Maybe a dim spot, if you are away from city skyglow and know where to look.
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"If they can't picture me with a knife, forcing them to strip in an alley, I don't want any part of it. It's humiliating." - windsock