Many people still don’t understand why Pluto was reclassified as a dwarf planet in 2006, including four-year old Charlie. Here, leading astrophysicist and Academy Fellow Professor Elaine Sadler explains Pluto's planetary demotion. | Australian Academy of Science

What is a dwarf planet, anyway? Watch this, and within 60 seconds, you'll know. Like NASA Dawn Mission for updates from the first spacecraft to visit a dwarf planet. | NASA Jet Propulsion Laboratory