More than half of the matter in our universe has so far remained hidden from us. However, astrophysicists had a hunch where it might be: In so-called filaments, unfathomably large thread-like structures of hot gas that surround and connect galaxies and galaxy clusters. A team led by the University of Bonn has now for the first time observed a gas filament with a length of 50 million light years. Its structure is strikingly similar to the predictions of computer simulations. The observation therefore also confirms our ideas about the origin and evolution of our universe. The results are published in the journal Astronomy & Astrophysics.