APOD: 2026 October 25 – Dark Matter in a Simulated Universe

Discover the cosmos!Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Explanation:Is our universe haunted? It might look that way on thisdark mattermap. The gravity of unseendark matteris the leading explanation for whygalaxies rotate so fast, whygalaxies orbit clusters so fast, why gravitational lenses so strongly deflect light, and howvisible matteris distributed. The featured image from theAmerican Museum of Natural History'sHayden PlanetariumSpace Show, Dark Universe, highlights one example of how pervasive dark matter might haunt our universe. In this frame from adetailed computer simulation, complex filaments of dark matter, shown in black, are strewnabout the universelikespider webs, while the relatively rare clumps of familiarbaryonic matter are colored orange. These simulations are good statistical matches to astronomical observations. In what is perhaps ascarierturn of events,dark matter-- although quite strange and in anunknown form-- is no longer thought to be the strangest source ofgravity in the universe. That honor now falls todark energy, a more uniform source ofrepulsive gravitythat seems to now dominate theexpansionof the entireuniverse.Tomorrow's picture:Orion the Great