Astronomers have spotted an unexpected and dramatic event in the early universe: a tightly packed collision involving at least five galaxies just 800 million years after the Big Bang.
The discovery, made using the powerful eyes of the James Webb Space Telescope, suggests that galaxies were growing, colliding, and reshaping their surroundings far earlier than scientists once believed.
The research was led by astronomers at Texas A&M University and published in Nature Astronomy.
It challenges long-held ideas about how quickly galaxies became complex in the young cosmos.
Before Webb began sending back data, most models predicted that large, complicated galaxy mergers would become common more than a billion years after the Big Bang.
Heavy elements such as oxygen—created inside stars and spread through space—were also thought to be rare at such early times.
This new finding shows that both processes were already well underway much earlier.
The newly identified system, nicknamed “JWST’s Quintet,” consists of several galaxies packed into a surprisingly small region of space.
While the galaxies are still tens of thousands of light-years apart, they are close enough to be strongly interacting and pulling on one another through gravity. For that era of cosmic history, this level of crowding is highly unusual.
Dr. Weida Hu, the study’s lead author, explained that astronomers normally expect early galaxies to be small, quiet, and relatively isolated.
Instead, this system shows a complex, multi-galaxy merger happening at a time when scientists thought such interactions were rare and simple.
The system was found using data from one of Webb’s deepest surveys of the distant universe, designed to capture faint and ancient objects.
Even more striking is how actively these galaxies are forming stars. Together, they are producing new stars at a rate about 250 times the mass of the Sun each year, far exceeding what is typical for galaxies in the early universe. This intense activity suggests that the merger is fueling rapid growth.
The team also discovered a large halo of glowing gas surrounding and linking the galaxies. This gas shines with light from ionized oxygen and hydrogen.
Oxygen can only be made inside stars, so finding it far outside the galaxies means it must have been pushed out during the collision. The results indicate that gravitational forces from the merger itself—not just powerful winds from stars—are spreading heavy elements into surrounding space.
This matters because it helps explain why Webb has already found many massive galaxies that appear surprisingly old and inactive just a few billion years later. If systems like JWST’s Quintet formed quickly through early mergers and used up their gas, they could naturally evolve into those massive, quiet galaxies.
Future Webb observations will track how the gas and galaxies are moving within this system, offering a clearer picture of how the first large cosmic structures took shape. Together, the findings suggest the early universe was far more dynamic—and chaotic—than scientists once imagined.
