Galaxies, the cosmic cities of the universe, explained by an astrophysicist

Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of Ask an astronaut and Space Radio, and author of How to Die in Space.

Galaxies there are shining cities, massive metropolises full of stars, dust, gas, black holes, magnetic fields, cosmic rays, dark matter and more. Separated by millions of light-years from basically nothing, galaxies are incredibly isolated, each island.