My students hate it when I tell them Pluto is not a planet. After all, many are from las cruces and even went to the Tombaugh school. But the one thing they hate even more than being told it, is when they work through the logic themselves and then decide it is not a planet. It raise tow interesting debates though.
The first stage of all science seems to be noticing and grouping. Then, after years of making new discoveries we always go back to the the grouping. Somehow we feel the need to reclassify
Second, who should make these decisions on reclassifying. The scientists or the public?