Hello Pluto: Nasa releases closest picture yet as probe approaches

New Horizons spacecraft captures sharp, close-up image as it approaches the dwarf planet on its flyby

By the standards of modern astronomical photography it might seem initially underwhelming - a grey-and-white sphere sitting amid the blackness - but make no mistake, this is a big moment for human scrutiny of the outer solar system.

To mark the moment when America's New Horizons probe made its closest approach to Pluto, passing within 7,700 miles (12,500km) of the last unexplored world in the solar system, Nasa released a picture of the dwarf planet from slightly further away.