Friday, July 15, 2016

1.2 MILLION GALAXIES

A map of the universe
Daniel Eisenstein and SDSS-III
"This is one slice through the map of the large-scale structure of the Universe from the Sloan Digital Sky Survey and its Baryon Oscillation Spectroscopic Survey. Each dot in this picture indicates the position of a galaxy 6 billion years into the past. The image covers about 1/20th of the sky, a slice of the Universe 6 billion light-years wide, 4.5 billion light-years high, and 500 million light-years thick. Color indicates distance from Earth, ranging from yellow on the near side of the slice to purple on the far side. Galaxies are highly clustered, revealing superclusters and voids whose presence is seeded in the first fraction of a second after the Big Bang. This image contains 48,741 galaxies, about 3% of the full survey dataset. Grey patches are small regions without survey data."

What you're looking at is a slice of  the entire universe, a web of galaxies billions of light years away. You're also looking into the past, since the further into the distance you look, the longer it took that light to reach your eyes. It all seems a lot smaller until you realize that each of those dots is hundreds of thousands of light years across.

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