How the Euclid telescope is building the largest 3D map of the universe

A recent update from the Euclid mission, launched via SpaceX Falcon 9 in July 2023, has produced an unprecedented 3D map of one-third of the sky, covering an area 500 times the size of the full moon.

Developed by scientists from the University of Edinburgh, the map is based on images captured by the mission’s 600-megapixel camera and includes over 100 million galaxies.

“This map of a large chunk of the sky is amazing,” says Andy Taylor, Professor of Astrophysics at the University of Edinburgh, indicating the telescope's ability to capture high-resolution images across immense areas​.

The Euclid mission, led by the European Space Agency, seeks to shed light on the elusive forces of dark matter and dark energy. These phenomena remain largely unexplained but are crucial to understanding the universe’s expansion and structure. By mapping the vast distribution of galaxies, Euclid aims to provide deeper insights into the nature of these forces, which have puzzled cosmologists for years.

The mission is expected to span six years, and aims to observe more than one-third of the sky, documenting billions of galaxies up to 10 billion light-years away.

A recent release from the space telescope showcases the 132 square degrees of the southern sky in pristine detail, capturing 14 million galaxies in a 208-gigapixel image.

The European Space Agency (ESA) described this image as “500 times the size of the full moon” as it appears from Earth.

This initial part of the map includes approximately 100 million sources, featuring both stars from the Milky Way and distant galaxies beyond. With its high-powered, 600-megapixel camera, Euclid captures enormous images, creating mosaics that will eventually form the complete cosmic map.

Secrets of dark energy and dark matter?

Euclid’s primary objective is to provide insights into two of the universe's great mysteries—dark matter and dark energy.

Dark matter, which constitutes roughly about 80% of the universe’s mass, binds galaxies together yet remains invisible since it does not interact with light. Meanwhile, dark energy, a mysterious force driving the accelerated expansion of the universe, is still poorly understood.

By observing distant galaxies, scientists can trace the impact and influence of dark matter on the bending of light—known as gravitational lensing.

Professor Taylor notes that these high-resolution images of vast swathes of the universe are “essential for Euclid's mission to understand dark matter and dark energy”.

The technology behind the telescope

The Euclid telescope uses both a visible light camera and a near-infrared spectrometer to capture cosmic phenomena with unprecedented precision.

“Before Euclid, we couldn’t observe the faint cirrus clouds in the Milky Way and pick out every star that’s illuminating them in super-high resolution,” Mat Page, lead for Euclid’s visible instrument, speaking to The Guardian.

This dual approach allows Euclid to observe galactic formations and the universe’s large-scale structure with remarkable clarity. Notably, it can detect faint “galactic cirrus”—gas and dust clouds that reflect optical light from the Milky Way, resembling the delicate cirrus clouds in Earth’s atmosphere, appearing as soft, light-blue streaks.

The mission involves more than 2,000 scientists from 16 countries, collaborating under the Euclid Consortium.

The University of Edinburgh, which also hosts the UK Science Data Centre for Euclid, plays a critical role in processing the immense troves of data collected, transforming them into actionable insights for the scientific community.

What’s next?

Since February, Euclid has so far mapped 12% of its survey.

In March 2025, a section spanning 53 square degrees, along with an initial look at the Euclid Deep Field regions, will be unveiled.

The first set of cosmology data from the mission will then be accessible to researchers in 2026.

“This is just the beginning of what we will be able to see in Euclid’s lifetime,” García Peñaloza adds to Space.com.

“For sure, the best is still to come! I’m positive Euclid will shed light on our understanding of the cosmic mysteries.”