Less than a decade ago, the human species completed our first reconnaissance of the solar system. The New Horizons spacecraft, after a journey of nearly five billion kilometers, flew past Pluto on 14 July 2015. Pluto was the last of the "classic" planets to be visited. For the first time we have seen a body in the outer solar system up close. We have imagined what Pluto is like since it was discovered 90 years ago. For the first time, we KNOW.
We will revisit the story of Pluto's discovery, explore why the classification of Pluto changed, and why we (both public and scientists) care! Pluto has always been the gateway to a much larger story --- the story of how planets are born and evolve with their parent stars. The demotion of Pluto is just one scene from the much larger debate we are having among ourselves about what it means to be called a "planet," and the story is not over yet!
We'll chat about what we know about Pluto, talk about the latest mysteries and results from New Horizons, and eventually return to the question: what is a planet, and should Pluto be one or not?