Nasa's New Horizons reached Arrokoth in 2019, revealing the early solar system

When Nasa’s New Horizons spacecraft left Pluto behind, its journey was far from over. The probe had already travelled farther than any spacecraft sent specifically to explore Pluto, but it continued into the dark outer reaches of the solar system. On 1 January 2019, New Horizons passed a small object in the Kuiper Belt that had never been seen up close before. The object, now called Arrokoth, was roughly four billion miles from the Sun and appeared in the spacecraft’s images as two rounded lobes joined at a narrow middle. It looked simple from a distance. Up close, however, its shape, surface and chemistry offered scientists an unusually well-preserved glimpse of the material from which the early solar system was assembled.Why Nasa named the Kuiper Belt object ArrokothNew Horizons launched in January 2006 with Pluto as its main destination. After using Jupiter for a gravity assist in 2007, the spacecraft continued towards the outer solar system and eventually made its historic Pluto flyby on 14 July 2015. The encounter transformed Pluto from a distant point of light into a world with mountains, plains, valleys and an atmosphere.The spacecraft did not stop there. Beyond Neptune lies...