i'm phil torres here with dr shini somara, and dr crystal dilworth. joining us is special guest dr mike brown. dr brown is a professor of planetary astronomy. he made many significant scientific discoveries, he's probably best known as the man who killed pluto. welcome to "techknow" dr brown, why did you do it? >> the obvious answer is did it have it coming. if it wasn't me someone else would do it. >> tell me the story. >> pluto never should have been called a planet. it was a mistake, just because everyone thought it was big when it was discovered, as big as june it ter and realised it was smaller and smaller. it is smaller than our moon. and there are thousands of other things out there just like it. >>> if pluto is not a planet, what is it? >> the official definition is work planet. which i like to think about things that look like planets. >> i love the story of the declassification of pluto. it's a great example of how new information can change the idea that a group of scientists have about something they take for time. >>> you came up with an