Ultima Thule is a small, icy world orbiting our Sun in the very distant reaches of the solar system. It lies beyond the orbit of Neptune, some 4.3 billion kilometers (2.7 billion miles) from the Sun. Ultima Thule was discovered on January 1, 2019 by NASA’s New Horizons spacecraft as it flew past this strange little world on its way to Pluto and the Kuiper Belt beyond.
This far-flung world is thought to be one of the most primitive objects in our solar system, a “building block” left over from the formation of planets some 4.6 billion years ago. Ultima Thule appears to be made up of two joined spheres, each about 20 kilometers (12 miles) across, making it look something like a giant snowman or a cosmic rugby ball. This unique shape has led scientists to nickname it “Ultima” (the furthest) “Thule” (the end).
Although much remains to be learned about Ultima Thule, its very existence offers tantalizing clues about how our solar system came to be. By studying this tiny world, scientists hope to gain insights into how planets form and evolve over time – ultimately helping us to understand our own planet Earth better.