The highest definition photo so far of the minor planet Ultima Thule in the Kuiper Belt has arrived from NASA’s New Horizons spacecraft. The probe took a multitude of photos of Ultima Thule, increasing in definition as the gap between them closed, with the highest-resolution images from the moment of closest approach still to come.
The first images to arrive were only a vague blur taken during the approach, leaving its exact shape a mystery: did it look like a bowling pin, or was it perhaps two small objects orbiting each other? This photo, which followed the next day, has revealed the object to be a cluster of two fused objects, a ‘contact binary’, in the shape of a snowman.
“The two lobes are perfectly separated, which implies that they must have merged extremely gently. Otherwise, they would have shattered,” said Dr Olivier Hainaut, astronomer at the European Southern Observatory. “This is not typical for other parts of the Solar System — look at the craters on the Moon for examples of what usually happens!”
Ultima Thule’s colour, as well as its shape, holds clues to its nature. “The two lobes seem to be of the same colour, and the…