Following on from its historic flyby of Pluto on July 14, NASA has selected the next potential destination for the unmanned spacecraft – a planetoid called 2014 MU69 that lies a billion miles beyond Pluto's orbit. The space probe will take over three years to reach this frozen remnant of the Solar System's earliest years.

Technically a small Kuiper Belt object, 2014 MU69 has been given the nickname "PT1" or "Potential Target 1" by the New Horizons team. According to NASA, it's less than 30 mi (45 km) in diameter and 10 times larger and 1,000 times more massive than a typical comet. It's this small size that makes it of interest to scientists, who regard PT1 as a leftover building block of the Solar System that's been preserved in the cold darkness of deep space and hasn't changed much in 4.6 billion years.