The ways that they detect planets around other stars is either by tiny fluctuations in movement (gravity from a planet is moving the star a little) or fluctuations in brightness (when a planet passes between the star and us.)

Distant bodies in our solar system take so long to travel in their orbits that we might be trying to figure things out with only 1% of the information.  It's fascinating how little of space we've actually looked at.

Keep talking like this and I'm going to think you're flirting with me.  ;D

Distant bodies in our solar system take so long to travel in their orbits that we might be trying to figure things out with only 1% of the information.  It's fascinating how little of space we've actually looked at.

To me, it's amazing that they can find planets rotating around distant starts and calculate whether or not they are in the habitable zone but they can't find a giant planet within our own solar system – that's how large our tiny little patch of the Milky Way is.

With Pluto I think they just got sick of having to use the phrase 'except Pluto':  The orbits of the planets do not overlap - except Pluto, the orbits of the planets are on the same plane - except Pluto….

The next planet-like object further out from Pluto is Sedna.