The largest 3D map of the universe

This extraordinary map allows scientists to study the structure of the cosmos and how it has evolved over billions of years. It was created using an instrument called the Dark Energy Spectroscopic Instrument (DESI), mounted on a large telescope in the United States. For five years, astronomers collected light from millions of extremely distant objects in space. Originally, the project aimed to observe around 34 million galaxies, but the results were astonishing and exceeded expectations: in the end, more than 47 million galaxies and quasars were mapped, along with around 20 million stars in the Milky Way. Each bright point in the map represents a galaxy: an immense collection of stars, planets, gas and dust. Our own galaxy, the Milky Way, is also part of this gigantic “cosmic design.” When scientists looked at the complete map, they discovered that galaxies are not randomly distributed. On the contrary, they form a kind of cosmic web made up of filaments, clusters and vast, almost empty spaces. This structure formed over billions of years thanks to gravity, the force that attracts objects with mass towards one another. By studying the arrangement of galaxies, astronomers can understand how the universe has changed over time. In fact, the map does not show only space, but also time. Some of the galaxies observed are so far away that their light has taken billions of years to reach us. Looking at them is therefore like looking into the universe’s past. Astronomers can see what the cosmos looked like when it was much younger, during a period known as “cosmic noon”: the time when galaxies were forming new stars faster than at any other stage in cosmic history. One of the main goals of this enormous map is to study one of science’s greatest questions: what is dark energy? Scientists believe this mysterious form of energy makes up around 70% of the universe and is responsible for the ever-faster expansion of the cosmos. By analysing the position and distance of galaxies in the map, researchers can better understand how the universe is expanding and whether dark energy changes over time. The astronomers’ work is not over: the DESI project will continue collecting data over the next few years to make the map even more detailed. This vast map of the universe will help scientists better understand the history of the cosmos and perhaps solve some of its deepest mysteries. After all, observing millions of galaxies does not just mean studying space: it also means trying to understand where the universe came from, and what its future might be.