Quote:
Originally Posted by Donnie B.
I'm not sure if this explains the different dates, but there is a difference between being "aligned with" the galactic plane and "crossing" that plane. One need not be aligned with a plane when crossing it, nor do you have to be crossing it to be aligned with it.
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As with everything else, the "galactic plane" (GP) isn't a line formed by viewing the edge of a surface. It's a zone which has a width due to something called uncertainty. Even if we knew precisely where all the matter in the Milky Way was and each particle's velocity, the GP would still be a zone due to influences from the Magellanic clouds, M31, et al, and other factors.
So it's constantly shifting as we peer farther into the galaxy using more and more of the electromagnetic spectrum. Using the term GP is sort of like saying that you're at the exact center of a fog bank.
Thus a term like "equatorial zone" would more accurately define what we know based on observation.