How do we explore tiny, faraway worlds?

For 85 years after it was discovered, Pluto was nothing but a faint, fuzzy dot, even in our best telescopes, smaller in our pictures than a single grain of sand held at arm's length. Then in July 2015, a piano-sized spacecraft that had flown for nine and a half years and three billion miles swept past Pluto and, for the first time ever, showed us a real world: ice mountains, smooth frozen plains, a pale blue haze. How do we possibly explore something so tiny and so impossibly far away?