Astronomers have long sought the origin of the universe, and hence ourselves as well. Using our best equipment, we observe that every galaxy cluster is rushing away from us, and from all others. For every extra one million light-years of distance, galaxy clusters recede 13 miles per second faster. When we retrace their paths we see that everything must have been in a single spot 13.8 billion years ago, which was right here. Clearly, the universe originated then and there. This week: The Big Bang!
The Big Bang
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NASA, ESA, and A. Schaller (for STScI)
