There is no way the Earth has passed, is passing, or will ever pass through the galactic center. On the other hand, the solar system does pass through the "central plane" of the galaxy. The sun bobs "up" and "down" as it orbits the galaxy, but slowly. I don't know the period offhand.
Look for threads started by rudeyd. There are lots of answers there that he's ignoring.
Fred
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"For shame, gentlemen, pack your evidence a little better against another time."
-- John Dryden, "The Vindication of The Duke of Guise" 1684
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