Where is Ultima Thule?
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Nasa mission to Ultima Thule: The where, what and why

Nasa's New Horizons probe is about to make the most distant ever exploration of a Solar System object. The spacecraft will fly past a 20-mile-wide block of ice and dust called Ultima Thule. As the BBC's Science Editor David Shukman reports, Ultima is a very long way from Earth.

  • 31 Dec 2018