Galaxy Shapes in an Attic
Pale Blue Pod
00:00
The Difference Between Spiral and Elliptical Galaxies
Spiral galaxies are younger and bluer than ellipticals, which tend to be older and redder. A spiral galaxy has a flat disk with the spiral arms in the disk, and the stars are moving in circles around that disk. An elliptical galaxy doesn't have those neat circular orbits. The shape of a spiral galaxy is maintained by the rotational motion of these stars around the galaxy.
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