What is a Galaxy?

Part of Hall of the Universe.

Galaxies AMNH/D. Finnin

Galaxies are titanic swarms of tens of millions to trillions of stars, orbiting around their common center of gravity. They also contain interstellar gas and dust. Galaxies show a range of shapes that astronomers group into three basic classes: spiral, elliptical, and irregular.

location (galaxies)
Our galactic neighborhood
The Local Group of galaxies contains a few dozen members, bound together by gravity. Of these, our Milky Way and the Andromeda Galaxy are the largest. Most of the others are faint dwarf galaxies. The Large and Small Magellanic “Clouds” are the most prominent satellite galaxies of the Milky Way.
AMNH/D. Finnin
Milky Way
observations of Milky Way galaxy [all wavelegnths in one]

In This Section

Exhibit Our Galactic Neighborhood The Local Group of galaxies contains a few dozen members, bound together by gravity. Of these, our Milky Way and the Andromeda Galaxy...