Astronomers from Johns Hopkins University have created an interactive map of the universe showing the positions and colors of 200,000 galaxies stretching to the very edge of the universe. The Sloan Digital Sky Survey (SDSS) telescope has been scanning space nearly every night for over 20 years. The telescope views different regions of the sky over time to create a comprehensive atlas at different scales, including 4 million stars in our Milky Way, galaxies in our Local Group, and others billions of light-years away.

Two astronomers from Johns Hopkins University, Brice Ménard and Nikita Starkman, combined SDSS data to create an intense visualization of part of the Universe. We’re under this “cosmic pizza slice”. From there, the map deviates 13.7 billion light-years from the present in space and time. And as much as a 10-degree wedge, which itself is only a tiny fraction of a giant sphere.

The map contains 200,000 tiny dots, each representing an entire galaxy containing billions of stars, planets, and other objects. The colors of these dots indicate the identity and properties of galaxies. The pale blue dots are spiral galaxies located 2 billion light-years from Earth. Then the dots start to turn yellow because elliptical galaxies dominate the map – they are brighter and can be seen from afar.

Between 4 and 8 billion light-years away, the card turns red. These are still elliptical galaxies, but light waves are “redshifted” or stretched to the red end of the spectrum “due to the expansion of the Universe”. After that, the map turns blue again – these are quasars, galaxies with very active supermassive black holes in the center that emit blue light.

As you get closer to the wider part of the map, the dots turn red again as the red eliminated quasars become the only thing still visible from such a great distance. And then, after a billion light years of almost complete darkness, we reach the edge of the observable universe. Although technically there is more of the universe beyond this limit, we can’t see it because light from that far hasn’t had enough time to reach us. With this map, the team set out to create a visualization of the universe that non-scientists could read, understand, and appreciate. Source