Galaxies, Supernovas, & Black Holes. Education 370 Joseph Lombardi. Galaxies. Galaxies are defined as vast collections of stars, dust, and gas held together by mutual gravitational attraction.
Galaxies are designated by their shape:
1- Introduction to Stars, Galaxies, and the Universe by Prof. Richard Pogge at Ohio State
2- Stars, Galaxies, and Cosmology by Dr. Daunt, Department of Physics and Astronomy-University of Tennessee.
3- Black Hole Formation