Astronomers Uncover the Massive Vela Supercluster Hidden Behind the Milky Way

In 2016, astronomers uncovered one of the universe’s most massive structures—the Vela Supercluster—hidden in plain sight behind the Milky Way. This colossal collection of at least 20 galaxy clusters, each containing hundreds of thousands of galaxies, spans roughly 300 million light-years, making it 3,000 times wider than our galaxy.

The supercluster resides within the Zone of Avoidance, a region obscured by the Milky Way’s dense dust, gas, and stars. This “dead zone” covers about 20% of the night sky, blocking astronomers’ view of what lies beyond. Now, a decade after its initial discovery, an international research team has mapped the Vela Supercluster in unprecedented detail.

Mapping the Hidden Giant

Published in a yet-to-be-peer-reviewed paper, the findings reveal the Vela Supercluster’s staggering scale. Using observations from South Africa’s Southern African Large Telescope (SALT) and the MeerKAT radio telescope, researchers detected galaxies deep within the Zone of Avoidance by observing hydrogen gas at radio wavelengths—waves that penetrate the Milky Way’s dust clouds.

“The millions/billions of stars forming the disk are so dense [and so] close to the galactic plane that we cannot easily see through it,” explained Renee Kraan-Korteweg, coauthor and astronomer at the University of Cape Town, in an interview with Live Science. “Moreover, where we have stars, we also have lots of minuscule dust particles, and like the stars, this dust layer gets thicker and thicker as you approach the plane.”

A Cosmic Structure of Unprecedented Scale

The Vela Supercluster is a coherent large-scale structure, comparable in size and mass to some of the largest known superclusters in the local universe. Its total mass is estimated at 30 quadrillion Suns (a million billion times the mass of our Sun), according to the research team’s statement.

In terms of size, the Vela Supercluster fits neatly between other mapped superclusters, such as:

• Laniākea Supercluster (which contains the Milky Way);
• Hercules-Corona Borealis Great Wall (the largest known structure in the observable universe).

Implications for Cosmology and Future Discoveries

The discovery of the Vela Supercluster offers new insights into the universe’s largest structures and their role in shaping cosmological models, including estimates of the universe’s age. Researchers suggest that more powerful radio telescopes could enable even more detailed mappings of the supercluster, refining our understanding of the cosmos.

“The findings could allow us to get a better understanding of the largest structures that dominate the universe and how they inform our current models of cosmology, including the age of the universe itself.”