Pluto flyby

The 29-cent Pluto 'Not Yet Explored' U.S. stamp. Source: USPS/collectSPACE

Listen: The Journey to Pluto Began Because Scientists Disagreed With a Postage Stamp

The Kuiper belt is a busy place. Credit: NASA/Johns Hopkins University APL/SRI/Alex Parker

NASA Mission Brings Pluto into Sharp Focus – but it’s Still Not a Planet