To make sense of who is out there, I generated a nice chart of “the neighbors” in our outer Solar System (Photoshop generated images based upon color and composition data and/or estimations for each body; the data are very limited for some of these); nicknames are in quotes, and the satellites of each are depicted beneath their respective planet-thingy (click on chart to enlarge):

In recent years, our Solar System has become both smaller and bigger. I thought I would chose this subject as the “What Is It? of the Week” because it is a little confusing and I thought I’d sort it out.
Last year, the International Astronomical Union demoted Pluto to the status of Dwarf Planet - the Solar System now only has 8 planets. A Dwarf Planet is defined as: 1). having an orbit around the Sun, 2). having sufficient mass to become a near-spherical shape, 3). not a satellite of another body in the Solar System (other than the Sun), 4). has not cleared the neighborhood around its orbit. Basically, a Dwarf Planet is a small planet with crap around it.
Much of the demotion of Pluto’s status can be attributed to the discoveries of Mike Brown, Chad Trujillo, and David Rabinowitz. In recent years, this team has discovered several bodies in the Solar System large enough to be considered “the next planet” or to cause Pluto to be redefined as a member of an extensive community of smaller planet-like thingies orbiting around the Sun. Among the larger Pluto-like planet-thingies, the Brown team has discovered Eris, Quaoar, Orcus, and Sedna. To add insult to injury to Pluto, it now appears that Eris is around 27% larger than Pluto; Pluto is not even the largest of the Dwarf Planets. Poor Pluto has gone through a lot in the last year. Eris, a rocky iceball (or icy rockball), was discovered in 2005 (by Brown, Trujillo, and Rabinowitz) and until its official naming in Sept 2006, it was nicknamed <nerd>”Xena”</nerd> and its moon (now called “Dysnomia”) went by <nerd>”Gabrielle”</nerd>.