Galaxies are likely to encounter other galaxies a few times over their histories.
Tidal Interactions Galaxies interact via Gravitation . Because of their large sizes, two galaxies passing near each other raise mutual tides . These tides distort the shapes of the galaxies Gives rise to dramatic effects without direct collision. Raising Tides Tidal stretching along the encounter line. Near side feels stronger gravitational pull from the companion Far side feels weaker gravitational pull and lags behind the near side.