Galaxies come in many shapes and sizes. No two are exactly alike, but they do tend to follow certain general forms.

Spiral galaxies

Spiral galaxies are flat with bright and dark arms winding around a central core. Some have bright bars across their centres or a bulge in the middle. The spiral shape comes from a wave of star formation that proceeds along the disk-like a wave of sports fans standing up in the bleachers. Our Milky Way galaxy is spiral shaped.

Elliptical galaxies

Elliptical galaxies are fat balls of old, cool stars. Most formed when spiral galaxies collided and lost their star-forming gas as they merged. Elliptical galaxies take either an ellipsoidal (like a U.S. football) or spherical (like a beach ball) shape.

Irregular galaxies

Some galaxies are neither elliptical nor spiral-these galaxies are called irregular. Irregular galaxies are small and take a wide range of forms. They are often distorted by the violence of star birth or stretched into odd shapes by the gravitational pull of neighbouring galaxies.
Canadian Heritage Information Network
Australian Museums & Galleries Online, Australia; Centre of the Universe; Gemini Observatory, Hawaii; Glenbow Museum; The Manitoba Museum; National Research Council Canada; Planétarium de Montréal

© Canadian Heritage Information Network, 2003

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