Gravity and Rotation main content.

Gravity and Rotation

Part of Hall of the Universe.

Gravity and rotation_HERO AMNH/D. Finnin
Everything in a galaxy orbits around the galaxy’s center.

The shape of a galaxy is a result of the individual orbits and their collective rotation. The force of gravity from all the stars, gas, dust, and dark matter holds a galaxy together.

Galaxy Shapes

The flattened disk of a spiral galaxy is evidence of the rapid revolution of stars, gas, and dust around the center. The orbits are nearly circular and share a common plane.

If, however, the orbits are tipped at all angles to one another, the galaxy has a round and puffy shape. Such an elliptical galaxy rotates very slowly.