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ScootysDad t1_j2ockk7 wrote

Reply to comment by modsarebrainstems in How do galaxies move? by modsarebrainstems

There's amble evidence that the Milkyway has collided with another galaxy and currently is in the process of incorporating another galaxy into its structure. The other galaxies are drawf galaxies so we maintained out spiral structure. With Andromeda we will not be a spiral any more.

Andromeda is slightly larger and it and 29 other galaxies (including the Milky Way) are part of the Local Group of galaxies. There may have been many more galaxes but they have since been incorporated through glactice mergers. Andromeda and the Milky Way's orbits around our center of gravity will bring about a merger in the distant future. By that I mean one of these galaxies are not in the stable orbit (on galactic time scale). Even after the merger the combined mass and velocity of the the merged galaxies will put us into a different orbit around our center of gravity.

You know what they say: If Andromeda doesn't come to us, we will come to Andromeda.

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modsarebrainstems OP t1_j2oglge wrote

So you're saying that because our mass isn't fixed, every time it changes we more or less move to a new orbit relative to our common center of mass? Is that basically correct?

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