The Milky Way is a spiral galaxy — but that's only one of the main morphological families astronomers use. Compare the shapes and real examples, then change your viewing angle to see why orientation can hide a galaxy's spiral arms.
SPIRALA flat, rotating disc with curved arms of young stars and gas — the Milky Way's shape.
ELLIPTICALA rounded, football-shaped collection of mostly old stars with little gas left to form new ones — no spiral arms.
IRREGULARGalaxies with no organized structure — often the result of a collision or a close gravitational encounter with another galaxy.
Change the viewing angle of the same disk-shaped galaxy. The spiral arms become harder to recognize as the disk turns edge-on. That does not turn it into an elliptical galaxy.
0° — Face-on. Curved arms are easier to recognize.
This is a geometric projection of one illustrative disk, not a physical 3D observation. Real spiral galaxies also contain central bulges, gas and dust, so their appearance depends on more than inclination.
NASA explains that viewing angle can conceal a galaxy's spiral arms. See NASA Science — Types of Galaxies and NASA Spitzer — an edge-on galaxy.
Astronomers also classify "lenticular" galaxies, a disc shape between spiral and elliptical, and many galaxies show mixed features.
Galaxy collisions — including the Milky Way's future collision with Andromeda — can transform spirals into ellipticals over billions of years.
Detecting alien worlds with light dips.
See where galaxies fit in the full scale of the universe.
What galaxies are actually made of, up close.