[Credit & Copyright: Ken Crawford (Rancho Del Sol Obs.); Collaboration: David Martinez-Delgado (MPIA, IAC), et al.]
Back in the 1970s my dad had a subscription to Scientific American. I recall an article on “colliding galaxies” where they had a number of photos of galaxies approaching, colliding, and then after they passed. They also used computer program to simulate the gravitational effects of two galaxies as they went through the process. A fascinating article for me to read when I was 15 or so.
I wish I still had that edition.