2015-01-07 科学新发现：重新发现冥王星-23（在线收听）

76 years after Pluto's discovery and after 17 years of research and development, Nasa's new Horizon Spacecraft sets out for Pluto. Travelling at around a million miles a day, it's on a 9-year, 700-million-dollar journey to reach Pluto and review its secrets.