By Stephanie Dwilson | 2026-07-27

From the far reaches of Antarctica, one of the world’s most powerful telescopes has just identified a historic new catalog of galaxy clusters, marking an important milestone in scientists’ understanding of the ancient universe.

By detecting subtle traces left by cosmic background radiation, the telescope is helping an international collaboration of scientists see thousands of massive cosmic structures for the very first time.

In early July, the University of Chicago announced that the South Pole Telescope (SPT) had identified thousands of galaxies that have never been listed in a scientific catalog before.

This discovery provides a "new window into the large-scale structure of the universe," the university said in a statement.

The telescope identified 8,892 possible galaxy clusters, 7,190 of which have been confirmed so far.

Nearly 20% of those had never appeared in any previous catalog. And for nearly 5,000 of the systems, it was "the first time the hot gas within these clusters has ever been detected," according to the University of Chicago.

"It's a new milestone for cluster cosmology to have this catalog as a resource," said lead study author Lindsey Bleem, a physicist at Argonne National Laboratory and senior associate at the UChicago Kavli Institute for Cosmological Physics.

"It will be the core of many, many studies over the years to come."

A galaxy cluster is a structure that contains "hundreds to thousands of galaxies, hot gas and large amounts of dark matter, all bound together by gravity," the University of Chicago noted.

These new clusters were found by looking for distortions in the cosmic microwave background. The results are published on the arXiv preprint server.

South Pole Telescope

The data was the result of five years of observations from one of the most remote and scientifically valuable locations on Earth: Antarctica.

The observations were taken by the SPT-3G camera, which was upgraded in 2017 and is currently the most powerful cosmic microwave background radiation camera in operation.

The South Pole Telescope itself is a 10-meter diameter telescope located at the National Science Foundation Amundsen-Scott South Pole Station.

It first began operating in 2007 at an elevation of 2,800 meters. This location was chosen to provide the telescope with a clear night sky view, unhindered during the months-long Antarctic winter nights.

The telescope’s primary mission is to study the origin of the universe by mapping cosmic microwave background radiation believed to be relic radiation left over from the Big Bang.

The SPT-3G camera’s overall mission is to shed light on some of the most compelling questions in astrophysics, including:

What is the universe made of?

What is dark matter?

What are neutrino masses?

Is general relativity the correct way to describe gravity?

When did the first galaxies and structures form, and how did they evolve?

What is the fate of the universe?

The latest discovery reveals that the South Pole Telescope is sensitive enough to study how conditions within galaxy clusters change over time.

International collaboration

The South Pole Telescope is primarily operated by the University of Chicago and funded by the United States via the Department of Energy and the National Science Foundation.

The European Research Council, the Kavli Institute for Cosmological Physics in Chicago, the United States Antarctic Program, and Antarctic Support Contract also contribute to funding and support.

The telescope’s multi-year observing campaign attracts researchers from institutions in North America, Australia and Europe.

Research groups involved in the collaboration come from Canada's McGill University and University of Toronto; Germany's Ludwig Maximilian University of Munich; and Australia's University of Melbourne.

They also come from US institutions: Argonne National Laboratory, Case Western Reserve University, Fermi National Accelerator Laboratory, Harvard-Smithsonian Astrophysical Observatory, SLAC National Accelerator Laboratory, and the University of California, University of Colorado and University of Illinois.