NASA Hubble's Field Guide to Galaxies

Galaxies are the visible foundation of the universe; each one a collection of stars, planets, gas, dust, and dark matter held together by gravity. Hubble’s observations give us insight into how galaxies form, grow, and evolve through time.

Hubble’s namesake, astronomer Edwin Hubble, pioneered the study of galaxies based simply on their appearance. He divided galaxies into three basic forms:

This “Field Guide” will quickly teach you those three basic forms, and some new ones that astronomers have added over the years!