Get an introduction to galaxies, from how they were initially observed on Earth, to the different forms they take, to the position of our own Milky Way galaxy.

Sebastian of Astronomic describes the structure and types of spiral galaxies in this lesson, delving into Edwin Hubble's classification system.

Sebastian introduces elliptical galaxies, from their shape and age, to their physical nature, to the black holes that lurk at their centers.

The Milky Way contains much, much more than just the Solar System! Sebastian of Astronomic describes the shape, origin, and qualities of this special galaxy.

Learn about the components of spiral galaxies, and how these features differ from galaxy to galaxy, and the two main theories as to how spiral galaxies form.

Learn about the shapes, features, and interactions of the third category of galaxy— irregular galaxies—which includes colliding and merging galaxies.

Active galaxies are luminous and highly energetic. In this lesson, Astronomic introduces two galaxy types with active galactic nuclei: Seyferts and quasars.

Explore your galactic neighborhood by learning all about the Local Group and the Local Supercluster of galaxies, of which the Milky Way is one of many members.

Astronomic explains the stages and composition of interstellar clouds of gas and dust, known as nebulae, and supernovas (or supernovae), explosive star death.

Dark matter cannot be seen with telescopes, and dark energy permeates all of space, expanding the universe. Learn about these physics mysteries in this lesson!