Ultima Thule has been described as a Frankenstein object, composed of "poorly formed snowmen".Read more
Science editor, BBC News website
The rock legend Brian May releases a song to mark the New Horizons probe's encounter with Ultima Thule.
Nasa's New Horizons probe is about to make the most distant ever exploration of a Solar System object.
Alan Stern, chief scientist on Nasa's New Horizons probe, looks forward to the flyby of Ultima Thule.
The American New Horizons probe is set to fly by a small icy body on New Year's Day, 2019.