Galaxies come in a remarkable variety of shapes and sizes; some are red and some are blue. Exotic names describe some of them: the “Cigar”; the “Black-Eye”; the “Antennae”. Additionally, while some galaxies inhabit the rich clusters of galaxies and have many thousands of neighbors, others exist in virtual isolation. During the course of their lifetimes, galaxies in such different environments are subjected to very a variety of interactions with their surroundings, sometimes triggering episodes of furious star formation or feeding their voracious central supermassive black holes. In this talk, we will discuss what the appearance of galaxies today can teach us about “extragalactic sociology”, how their lives are affected by their environments.

This Public Lecture by Prof. Martha Haynes, of Cornell University, USA is part of the University of Portsmouth’s annual public lecture series.