By measuring the motion of the galaxies in a cluster, astronomers can infer the cluster's mass.
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Related: galaxy, cluster, infer
Prev: According to previous speculation, these strands were gases that had been blown out by an explosion in the galaxy.
Next: In a very real sense light pollution causes us to lose sight of our true place in the universe, to forget the scale of our being, which is best measured against the dimensions of a deep night with the Milky Way — the edge of our galaxy arching overhead.
