The Sloan Digital Sky Survey is an amazing project: map out the positions and colors of objects in the sky to high precision. In the case of galaxies, the colors can be use to get a decent estimate of the distance; galaxies moving away from us as the Universe expands get their colors subtly changed versus distance.
Using this data covering an incredible 1/4 of the entire sky, astronomers created the map above of 900,000 luminous galaxies: ones that are brighter than usual. By choosing these overachievers they can see them at great distances, and make a complete map. This map, the largest ever compiled, shows each galaxy as a single green dot, and stretches out to a distance of 6 billion light years -- halfway across the Universe. The galaxies can be seen to cluster in some spots, and this tells us about conditions in the early cosmos when these clusters formed. Astronomers using these data have constrained limits on such disparate things as dark energy and neutrino mass!
They also put together a very cool video
where they move the data around in 3D. It's mesmerizing... especially when you think that to do this in real life you'd have to travel at trillions of times the speed of light!Original SourceCredit: David Kirkby (University of California, Irvine) and the SDSS-III Collaboration