Map the universe in 3D
But accomplishing this technical feat wasn’t the only hurdle DESI had to overcome.
Although the basic image of the sky is visible to anyone looking up at night, creating accurate maps is a little trickier. Especially in 3D, because what we see when we look up is a 2D projection of the 3D cosmos. Before DESI could even begin, researchers needed to create a more detailed 2D map of the universe. What followed was a 6-year effort, bringing together over a billion images of galaxies drawn from over 200,000 telescope images and years of satellite data. The new card includes an incredible 1 petabyte of data – enough to store 1 million movies.
With this new 2D map in hand, DESI began probing the skies on May 17, 2021.
Addressing the Big Question
The universe has grown steadily since it began. This expansion pushes all matter, including galaxies, out into the cosmos like raisins embedded in a loaf of raisin bread. As they recede, the light reaching us from distant galaxies is stretched into longer and longer wavelengths. Generally, the more a galaxy’s light is stretched or red-shifted, the further away the galaxy is.
By collecting detailed color images of galaxies, DESI can determine how much of each galaxy’s light is redshifted. And that adds the third dimension – depth – to our picture of the universe.
By knowing the distances of galaxies and other bright objects, astronomers can paint a better picture of how the universe became the place we see it today.