Ahh, the Pluto wars, round 4384. It’s amazing how people can get so emotional about an iceball that’s 3 billion kilometers way. Especially when it’s a dog planet, not a real planet.
My take is that the IAU shoudn’t have tried to define the word planet. After all the geologists have not done the same for the word continent, as Mike Brown points out in his book. But since they did, they should have gone for a much simpler definition.
Count me amongst the heartless Antiplutoists. The situation was becoming confusing and nobody could tell how many planets there were in the solar system any more. That’s a select club and we don’t want to let in any shmuck pretending to be a planet, or else we would be overwhelmed by a crowd of dirty iceballs. Next thing you know, the asteroids would want to join too.
The planet’s maximum distance from the Sun (at aphelion) will be longer than the semi-major axis, and its minimum distance (at perihelion) will be shorter. That’s because the Sun isn’t at the center of the elliptical orbit; it’s at one of the foci.