Cosmic collisions and cannibalism - The 2026 Kavli Prize in Astrophysics' science explained

Professor Jim Al-Khalili explains the science behind the Kavli Prize 2026 in Astrophysics. For decades, the Milky Way was seen as a stable, beautiful spiral. The 2026 Kavli Prize recipients in Astrophysics, Amina Helmi from ‪@universityGroningen‬ , Vasily Belokurov from ‪@cambridgeuniversity‬ and Rodrigo Ibata from ‪@unistra‬, have overturned this idea. Using the most precise instruments available, the scientists have effectively performed cosmic archaeology. They’ve analyzed vast, stretched-out structures of stars, known as stellar streams. These are the visible wreckage of smaller dwarf galaxies ripped apart by the Milky Way's gravity, providing a detailed record of the galaxy's history of mergers. This work has shifted the paradigm of galaxy formation from a slow, steady state to a dynamic, violent narrative of galactic cannibalism. Most importantly, these streams act as cosmic seismometers. By measuring how the stars are moving, scientists are measuring the galaxy’s gravitational potential, allowing them to map the distribution and structure of the elusive dark matter, the invisible scaffolding that holds the Milky Way together. The discoveries have also fundamentally altered how we conceive of the universe: galaxies are not just collections of stars; they are living historical objects, constantly being born, damaged, and rebuilt by the gravitational dance of massive cosmic mergers. Produced by Furnace TV for the Kavli Prize #astrophysics #astronomy #space #kavliprize