Astronomers know that the Andromeda Galaxy is drifting toward the Milky Way, but exactly what happens when two giant disks of gas, dust and dark matter swirl together is still an open question. Using a publicly available galaxy-simulation toolkit on a university cluster, the team set up virtual versions of both galaxies, then let gravity do the rest—fast-forwarding ten billion years in just a day of computing time.

The model tracks millions of “particles” that stand in for gas clouds, stars and dark-matter clumps. As the galaxies brush past each other, tidal forces pull long streams of material into space. Where the gas is squeezed hardest, shock waves set off bursts of star formation. Measuring that rate matters: it tells us how bright the merged system—nicknamed “Milkomeda”—will shine and how much heavy-element “stardust” will seed future planets.

In the baseline run, the limited gas supply allows only a modest uptick in star birth before the two disks finally settle into a football-shaped galaxy. The work, which earned 4ᵗʰ place in Geo- & Space Sciences at the German national youth finals, shows that our night sky in four billion years will glow, but not explode, with newborn suns.