Video: New Horizons animation

Two of Pluto’s mini-moons, the mysterious Nix and Hydra, have transitioned from featureless points of light into their own worlds with new imagery from NASA’s New Horizons spacecraft.

Five years ago Tuesday, NASA’s New Horizons spacecraft barreled by Pluto for a high-speed encounter that gave humanity its first close-up look at a distant world that puzzled astronomers and planetary scientists for nearly a century. Scientists are now planning how to go back.

New Horizons project manager Glen Fountain, a veteran of nearly 50 years at the Johns Hopkins University Applied Physics Laboratory, told the Pluto probe’s team to live in the moment for Tuesday’s historic flyby, but look out for last-minute snags.