A giant supercomputer is making massively detailed models of the cosmos. Next month, the world’s third-fastest supercomputer --known as Mira--will complete tests of its new upgraded software and begin running the largest cosmological simulations ever performed at Argonne National Laboratory. These simulations are massive, taking in huge amounts of data from the latest generation of high-fidelity sky surveys and crunching it into models of the universe that are larger, higher-resolution, and more statistically accurate than any that have come before.