Scientists have uncovered a major clue about our cosmic neighborhood. Researchers discovered that the Milky Way sits inside a huge, flat sheet of dark matter. This sheet stretches tens of millions of light-years across space.
The team, led by Ewoud Wempe from the University of Groningen, ran detailed computer simulations. They started from the Big Bang and built our Local Group step by step. The Local Group includes the Milky Way, Andromeda, and nearby galaxies.
For decades, experts puzzled over one mystery. Edwin Hubble noticed galaxies move away from us almost 100 years ago. However, most nearby large galaxies drift outward too. They ignore the strong gravity from the Milky Way and Andromeda. Only Andromeda approaches us at about 100 km/s.
Now, the simulations reveal the reason. Most matter just beyond the Local Group forms a wide, flat plane. This plane measures about 10 megaparsecs, or roughly 32 million light-years. Above and below it lie enormous voids with very few galaxies.
This flat structure balances forces cleverly. The Local Group’s gravity tries to pull galaxies inward. At the same time, distant mass in the sheet pulls them outward. As a result, galaxies experience almost no net inward pull. They follow the universe’s smooth expansion quietly.
The voids play a key role too. They contain little mass to drag galaxies inward from other directions. Therefore, the setup matches real observations perfectly. It also fits the standard cosmological model without contradictions.
Moreover, the sheet includes both visible matter and invisible dark matter. Dark matter dominates this hidden structure. The findings come from an international collaboration with experts from Germany, France, and Sweden.
The study appeared in Nature Astronomy. It marks the first detailed look at dark matter distribution around our Local Group. Scientists now better understand why our galactic neighbors behave this way. This breakthrough solves a long-standing cosmic puzzle.