Our closest neighboring galaxy may be a lot closer than you think. The planet Earth is now at a half-way point, passing through remnants of Sag-DEG.
Staring up at the sky long enough, our astronomical brains start getting into the math of everything, with vector measurements, velocities, trajectories and, most importantly, how it all works together.
Over the past couple billion years, the Milky Way has been rough-housing with Sag-DEG, that would be the Sagittarius Dwarf Elliptic Galaxy, the bulk of which is located on the far-side of the galactic core. It’s located within the spiral disk of the Milky Way and is about as far from the core as is the solar system. The smaller elliptical galaxy was gravitically drawn off-course toward the supermassive black-hole at the center of the Milky Way. The stretched-out ellipse is now a trailing ring of stars that orbit the Milky Way at approx. 60 degrees inclination from the spiral disk. It is believed a good chunk actually met its fate with the black hole and our Southern Hemisphere’s Magellanic Clouds (both major and minor) appear to be remnants of that collision.
As I stated at the beginning, Earth is passing through that Sag-DEG ring right now, and the closest intergalactic star may be just a handful of lightyears away.
And, just in case you were wondering … as I was:
Is the Sun from Another Galaxy?
Bad Astronomy-guy Phil Plait has always been a Habitable Zone favorite, a living, breathing, ready and able combatant against the push of pseudo-sciences the world-over. I recall he used to give movie reviews for flicks with Bad Astronomy … probably still does. Star Trek took a pretty good hit from him, but I’m surprised Star Wars survived him at all.