Poor Pluto. After all these years, its status killed, kicked off the list of planets.
Much-maligned Pluto doesn't make the grade under the new rules for a planet: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit."
Pluto is automatically disqualified because its oblong orbit overlaps with Neptune's.
Instead, it will be reclassified in a new category of "dwarf planets," similar to what long have been termed "minor planets." The definition also lays out a third class of lesser objects that orbit the sun — "small solar system bodies," a term that will apply to numerous asteroids, comets and other natural satellites.
As a colleague said, "Not only are we screwing up this planet, now we have to mess with the whole solar system." Now, all of ys who learned the planets in order from the sun with that nifty mnemonic (My Very Excellent Mother Just Sent Us Nine Pizzas) will have to come up with another one. Just Sent Us Nachos?
It's been much remarked that we are living through a knowledge explosion, with the amount of available information doubling every two or three years. Some of it results from our exploration of things we couldn't fathom before, such as the human genome, but much of it comes just from refining how we look at things we already know. Nothing has changed in the solar system. We're just defining it more precisely.
