What's a Planet? (A Think)

The New York Times is running an article entitled, For Now, Pluto Holds its Place in Solar System. The article begins:

In the hope of ending years of wrangling, a committee of astronomers and historians has proposed a new definition of the word “planet” that would expand at a stroke the family of planets from 9 to 12 and leave textbooks and charts in thousands of classrooms out of date.

One point of this article, seems to be that science continuously evolves. What we know now may be further supported or disproved by what we learn tomorrow. It's important for students to recognize that knowledge evolves. If they continuously seek to learn new things the knowledge that they learned yesterday will come to be understood differently.

Lesson Ideas:
1. Ask students if they think that it's important to have a precise definition for the word "planet." Encourage them to support their opinions.
2. Ask students if its fair for a group of scientists to get together and together choose the appropriate definition for the word "planet." Encourage students to consider why these scientists have the right to form definitions. Explain that if people didn't define words, words would not have meanings.
3. Encourage students to research the distance between Pluto and the other planets in our solar system.
4. Ask them to write a diary entry pretending that they are on the icy planet of Pluto. What would life be like?
5. Check out the site Windows to the Universe for a lot more information on planets and outer space.