On New Year's Day, NASA's New Horizons spacecraft is expected to make history by conducting the most distant flyby ever, by zooming past an object a billion miles past Pluto. It's called "Ultima Thule," meaning "beyond the known world."
Why it matters: The spacecraft, which is the same one that sent back dazzling images of Pluto in 2015, is slated to be the first to explore an object in the Kuiper Belt — a region of icy bodies beyond the orbit of Neptune that are thought to be leftovers from the solar system's early days.
