From YouTube, produced by Spitzer Science Center
Ask An Astronomer, question asked is: Why isn't Pluto a planet any more? Dr. Robert Hurt explains why Pluto got... well... plutoed. Describes how we define the word planet. Explains when planets were discovered, how asteroids were discovered, and how Pluto was discovered. In early 1990's astronomers found items bigger than Pluto. In August 2006, astronomers from all over the world met and decided on a formal definition of a planet-Pluto didn't make it! It is good to know though that even they make mistakes. Video is of good quality and is appropriate for middle elementary school and middle school students. Run time 03:31.