This post surrounds the topic of Pluto. I previously sent some of this information to my family in an email, but I'm updating it to clarify the point I was trying to make.
There is this misconception on how science works in our society, and it often rears its ugly head in regards to Pluto. It is the idea that science can't be trusted because it is always changing. Pluto is used as an example based on the idea that "it used to be a planet, but now it's not!" The reality is that the declassification of Pluto as a planet has nothing to do with scientists just changing things on a whim as such statements imply. Rather, the change had much to do with obtaining new data.
That new data surrounded the discoveries of other round, planet-like bodies in the beginning of the last decade. Three of these newly discovered bodies, as well as Pluto, were then classified as "dwarf planets." These dwarf planets include Haumea, Makemake, and Eris. Eris is about three times further away from the sun than Pluto (though its orbit varies so much that, at Eris's closest point to the sun, it is closer to the sun than Pluto if Pluto were at its furthest point). Perhaps more importantly to this discussion is that it is thought to be more massive than Pluto and could have potentially been the 10th planet of the solar system. This fact was a motivational factor in getting the International Astronomical Union to define what a planet is.
Additionally, there is a body known as 90377 Sedna that can get up to about 31.6 times further away than Pluto! Another interesting tidbit is that there is another dwarf planet that is in the asteroid belt, called Ceres. Also interesting is that, according to Wikipedia, "for half a century it was classified as the eighth planet." (This would have been before the discovery of Neptune or Pluto.) So, here we are talking about how "Pluto is no longer a planet" when the same thing happened to Ceres many years ago!
With all of this information, either these bodies would also have to be classified as planets or else what is classified as a planet had to be changed. It was the classification that changed.
What people really need to do, though, is stop thinking about this as change. Do people care, for example, that cellular phones can now browse the Internet, record video, play music, etc. when only a decade ago they could do no more than make phone calls? Do people care that televisions now have 3D technology? No...with the possible exception of being upset that they cannot afford the latest technology. They often welcome the change. Nor would most people call this "change." They would more likely call this "advancement" or "improvement." People need to start thinking in these terms when it comes to other aspects of science, including the reclassification of Pluto. This should be thought of as an advancement or improvement of our understanding of the solar system in which we live and not a change.
Science does not "change." It improves, advances, and refines.