>>14283827Major galaxies don't really have orbits, they have trajectories. It's because at that scale things like expansion of space start to matter more than speed, they are so massive they can't really be effected by anything other than other galaxies and even then quite weakly and any "orbit" around some arbitrary point can be so long that the galaxy is literally dead before that happens even once. There are satellite galaxies though, large magellanic cloud orbits around milky way with something like 1.5 billion year orbit but is going to merge with milky way in 2.5 as well as some others with again billion year orbits, during which they might shrink or grow by a factor.
How galaxies move simply doesn't fit any real definition of what an orbit is.
