The Magellanic Clouds are a pair of dwarf galaxies passing the Milky Way probably for the first time, but as they move they have been interacting with each other for billions of years.

Trouble near the Milky Way: The Large Magellanic Cloud is ripping its smaller neighbor galaxy apart

Source: space
Source Link: https://www.space.com/astronomy/galaxies/trouble-near-the-milky-way-the-large-magellanic-cloud-is-ripping-its-smaller-neighbor-galaxy-apart