In the early hours of New Year’s Day, NASA’s New Horizons spacecraft hurtled past Ultima Thule, the most distant space rock we have ever visited.
Ultima Thule is located in the Kuiper belt, some 6.6 billion kilometres from Earth. Though low in resolution, the images sent back by the probe suggest that it is shaped like a bowling pin with two unequally sized bulbous ends.
The object is around 32 kilometres long and at most 16 kilometres wide. It appears to be spinning like a propeller, with its axis pointing towards New Horizons. However, we can’t yet rule out the possibility that it is actually two objects orbiting each other.
New Horizons began its long journey in 2006, reaching its primary destination, Pluto, in 2015 before changing course for Ultima Thule. It will send back more images from the rock in the coming months, along with data on its surface composition and temperature.
The Kuiper belt is made up of remnants from when the solar system formed, so this information may teach us something about the origin of planets including Earth. New Horizons will continue to explore the Kuiper belt until at least 2021.