How far does it stretch? Where does it end… and what lies beyond its star fields… and streams of galaxies extending as far as telescopes can see?

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In ancient times, most observers saw the stars as a sphere surrounding the earth, often the home of deities.

The Greeks were the first to see celestial events as phenomena, subject to human investigation… rather than the fickle whims of the Gods.

One sky-watcher, for example, suggested that meteors are made of materials found on Earth… and might have even come from the Earth.

Those early astronomers built the foundations of modern science. But they would be shocked to see the discoveries made by their counterparts today.

The stars and planets that once harbored the gods are now seen as infinitesimal parts of a vast scaffolding of matter and energy extending far out into space.

[,,,]
Recent precision measurements gathered by the Hubble space telescope and other instruments have brought a consensus…

That the universe dates back 13.7 billion years.

Its radius, then, is the distance a beam of light would have traveled in that time … 13.7 billion light years.

That works out to about 1.3 quadrillion kilometers.

How Large is the Universe?


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