Transcript for ARCHIVAL VIDEO: Astronomers Demote Pluto in 2006
We have set ourselves a difficult task tonight to take a closer look. At something more than two point six billion miles away. Now we all learned the planet's in school Mercury Venus earth Mars Jupiter Saturn Uranus Neptune. And then the little bitty guy all the way out there Pluto. Nine planets everybody learned that in school. But Pluto got ignominious Lee dumped today and now all the school books are gonna have to change why. Here's ABC's bill where. It is small it is cold. It is a celestial odd ball so far out elapse the sun once every 248 years but still. An elite member of the planet club. Until today. The recommendation. Is. That we can sit there are no to be in a special. Off that's right special. In the most demeaning sense of the word according the world's top space scientist Pluto is now an icy dwarf. Bigger than an asteroid. Not quite a planet. It's basically a comets around iceberg. Circling in the outer part of the solar system Pluto doesn't control the orbit of anything else and as such it doesn't. Deserve to be an issue can be called planet would total was first discovered in 1930 scientists thought it was a lot bigger than it actually is. Now what modern telescopes we know it's five times smaller than earth. 62 times smaller than Jupiter. And because there's so many chunks of ice like this it's really not that important but. Try telling that to the fans. Arab when they would. Pluto is the most beloved icy rock. Most people have never seen. How can we possibly booted out of the solar system club aren't we being mean aren't we being exclusive aren't we being elitist know. Were simply coming to a new level of understanding. And it's in general have always been sort of are part of our our mental landscape does have one that taken away as very painful. Even so the universe will have to adapt slowly since school districts go years between bulk purchases. Some kids won't get their updated science books until when he tan. Puzzles will be reprinted planetarium was repainted. And an updated obituary for Clyde Tom -- the Kansas farm boy who discovered Pluto. Instead of spinning in a grave tonight combos ashes are actually on board NASA's new horizon rockets. Which will whiz past that certain famous icy dwarf eight years from now. Bill we're ABC news New York.
This transcript has been automatically generated and may not be 100% accurate.