Year of the Comet
Comet C/2011 L4 (PANSTARRS)

PANSTARRS information

Comet C/2012 S1 (ISON)

ISON information

Ask Astro

Published: April 26, 2010
m80 globular cluster
One of the densest globular clusters in the Milky Way, M80 is located roughly 28,000 light-years from Earth and holds hundreds of thousands of stars.
Photo by AURA / STScI / NASA
What keeps these clusters from collapsing is the angular momentum of the stars as they orbit the cluster's center of mass. It's the same physics that keeps the solar system from collapsing.
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