"It's as if we had traveled the world and only found large dogs like the Labrador and never found the Chihuahuas. Well, would we say they're not dogs just because there's too many of them and we can't keep track of their names and they are smaller?"
Stern is highly critical of the IAU's decision to restrict the solar system to just eight planets - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune - and many minor worlds that don't "fit" with the new planetary definitions.
"When you list the characteristics of the dwarf planets, they have solid surfaces, atmospheres, seasons and polar caps, cores and often satellite systems; all the same attributes as the larger planets, except they're just a smaller version."
Brown, who lightheartedly calls himself "Pluto Killer" on Twitter (as his discovery of Eris ultimately led to the IAU vote on what a planet actually is), also discussed the huge amount of variation in Kuiper Belt objects and commented on how Eris and Pluto size up:
"One thing we know very well is that Eris is 26 percent more massive than Pluto, which is actually quite a big amount. The total extra mass that Eris has compared to Pluto is more than the mass of the entire Asteroid Belt - this is not an insignificant amount of extra mass ... the fact that (Pluto and Eris) are the same size makes people say they are ‘like twins,' but the fact that they are the same size, I think, makes them