The Sloan Digital Sky Survey (SDSS) is an ongoing endeavor to map the sky in great detail, with many different goals. One of the larger objectives is to map the structure of the cosmos by determining the positions of galaxies and their relativistic redshift (basically their distance). Using this data and Mathematica, you can plot the information and reveal the structure of the cosmos.

In my spare time, I queried the SDSS website, which is database driven, and in eight separate queries I was able to get all galaxies in the survey out to a redshift of 0.5. According to Wolfram|Alpha, this corresponds to looking back in time 5.02 billion years ago, or a distance of 6.14 billion light years, when the light we’re now seeing from the most distant galaxies started its journey here. That’s a billion years before our solar system formed. It’s taken this long for the light to reach us.



This animation is of only a tiny fraction of the visible universe, but still more than enough to give you a glimpse of the size and scale of the universe.

Each point represents a galaxy. Our galaxy would be at the very center (no, we aren’t the center of the universe—just the center of this animation). As you can see, galaxies tend to cluster along a web-like structure with “voids” interspersed. The survey images the sky in slices, which form the wedge-like pieces in the animation. These are the areas of the sky imaged so far.

The well-known Hubble Ultra Deep Field, while imaging galaxies to a much greater distance (about 13 billion years ago and redshifts between 7 and 12), covers only a tiny pinprick of the sky (11 arcminutes) and so doesn’t show the structure that this animation does.

This was achieved in Mathematica with a very tiny amount of code: