New Horizons on course for Pluto flyby on Tuesday

It's three billion miles away (4.7bn km) and has never been seen in detail but now Pluto, at the very edge of the solar system, is on the brink of being revealed in a new light.

On Tuesday, Nasa's New Horizons spacecraft will sweep past the icy dwarf planet and send back the clearest ever images of it.

David Shukman reports.