DESI Year-3 Data Slice

This shows a small fraction of the total DESI year-3 data in which the structure created by gravity is visible. This is the largest 3D map of the Universe ever made. 

This structure is a huge web shaped by gravity, with most galaxies and galaxy clusters lying along the strands.

A completely homogeneous Universe would have no stars, galaxies, or planets. As it turns out, when our Universe began, it was almost completely homogeneous, with the seeds for everything we see in the sky likely coming from disturbances in the tiny fraction of a second after the Big Bang. These were subatomic fluctuations in the density of the primordial soup of quantum particles that stretched out as the Universe expanded until they were bigger than any galaxy. Where the density of particles was higher, gravity attracted yet more particles, especially dark matter. The dark matter in turn attracted ordinary matter, and galaxies and galaxy clusters grew where enough material collected.

The result is the large-scale structure of the Universe that we see in this image, displaying a map of those primordial fluctuations with long strands, sheets, and clusters of galaxies forming a huge web. The web is punctuated by voids, which have few or no galaxies.

On even grander scales, what became galaxies and clusters began as froth on huge cosmic sound waves during the era when the Universe was a hot cauldron of particles and light. These waves are called baryon acoustic oscillations (BAO), and they provide us with a way to measure the expansion rate of the Universe, including the mysterious acceleration caused by dark energy.

Explore the galaxy structure of the giant zoomable image here.