Ummm... Plutos' satelite is Charon. Pluto and Charon do share a binary point, making them a double planet, but Charon still counts as Pluto's satellite as it orbits a barycenter oriented with a bias to pluto (i.e. the common point is cloer to pluto than Charon).

The new IAU definition places pluto as a Dwarf Planet, along with Eris and Ceres. Pluto failed the planet test on point 2.

(1) A planet is a celestial body that (a) is in orbit around the (or a) Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrosstatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

(2) A "Dwarf Planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape [2], (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite

(3) All other objects [3], except satellites, orbiting the Sun shall be referred to collectively as "Small Solar System Bodies"

For planets you have a few possible types (classification mostly swiped from 2300ad:)

Rock: It's a rock, Jim. Desolate, airless, radiation blasted surface of , well.... rock. Might be useful for mining or weapons testing, or perhaps playing golf. Example: Mercury

Hothouse: A runaway greenhouse effect has produced massive tempratures on the planets surface. Other delightful features may include acid rain, continent sized electrical storms capable of fusing rock to glass, 600mph winds (with acid rain), crushing pressure and noxious atmospheres. Suprisingly, this is not incompatible with some suggested forms of life. Not that you'd want to ask them to a dinner party, though. Example: Venus

Garden: A wide ranging definition, but ulrimately a planet capable of supporting life unaided on it's surface. That dosent mean you could frolic naked, but you don't need an artificial environ ment (i.e. a suit or ship, to survivce. Can include worlds much colder or warmer than humans are used to, or those with stronger or weaker gravity. Example: Earth

Desert or Post Garden: Loss of atmosphere, increasing radiation and reduction of a worlds hydrosphere all result in a desertification of a planet. Thin atmosphere and low pressure and tempratures results in mater evaporating/boiling or freezing, leaving the surface arid. Atmosperic gasses may be bound up into the surface in some way to reduce the atmosphere even further. Radiation, temprature and atmospheric pressure at the surface are all too low to support life unaided, but conditions are not as hostile as on a rock or houthouse. Example: Mars

Gas Giant: A huge body, usually in the order of 10+ Earth masses, composed of mainly hydrogen and helium with some water ice and methane. The planets have non true solid surface, but are a a smooth transition from gasses at the cloud tops through liquids in the core. Some planets MAY have a pressure induced solid at their core - metallic hydrogen and diamond have been suggested, but it's not required. A subset of gas giants are known as ice giants because of the different composition of the gasses, water ice and methane and ammonia may predominate over hydrogen and helium. Ice Giants tend to be smaller than Gas Giants. Example: Jupiter (Gas Giant), Neptune (Ice Giant)

Iceball: A small, frozen world. Essentially a rock that has had an atmosphere that has frozen. Tempratures are very, very low as the planet is too far from it's parent sun to recieve much solar radiation. Example: Pluto

Brown Dwarf: Larger than a gas-giant (13-70 Jupiter masses), smaller than a star. Brown dwarves are planets that have sufficent mass to radiate due to graviatational contraction, but don't have enough mass to start the proto-steallar fusion reactions to be come a true star. The most massive objects to be classified as a planet, they may produce enough radiation to have their own life-bearing satellites. The larger masses may fuse some elements, such as Deutirium or lithium, but don't start the true fusion process until you are at somewhere around 80 Jupiter masses. Example: Gliese 229B

Exotic: Beynd these base definitions you have all sorts of exotic planets, Cthonian planets (gas giants stripped of their atmospheres), Hot Jovians, failed cores, Carbon planets, pre-garden, post garden and so on.

Sorry, I meant it failed to qualify as a planet since it hasn't cleared it's own orbit - there are still large amounts of other icy junk inside an out of Plutos orbit. Arguably it isn't in orbit around the sun either, it's in orbit around the barycentre with Charon, which itself is in orbit around the sun.

G.

It takes a long time and concerted effort to make these calculations about each individual star and as one article mentioned they havn't performed distance calculations on most of the stars we see. The brown dwarf in question may be plainly visible. Also the wobble may be detected, but as we are seeing with that new planetoid, they have to make long term observations to be sure. And at that point, just because you're pretty sure you see a wobble doesn't mean you can instantly find the culprit. It will take a lot of searching.

Paralax calculations require ploting an exact location of the star relative to extremely, extremely distant background stars/galaxies and ploting it again six months later, when the Earth is at the opposite side of its orbit. Then you can do a simple geometry formula. A lot of adjustments have to be made, of course (as the orbit is an ellipse not a circle, for example), but those are relatively minor. Then you can come up with a fairly approximate distance.

Just something to keep in mind. Astrophysicists far more capable then I are working through the concept and will make a determination one way or another.

However, for SF gaming, throughing a distant brown dwarf out towards or beyond an Oort cloud would prove very interesting. Is it the location of a secret installation? Are pseudo planets or asteroids or moons orbiting it? Was it a natural binary or an ancient rogue dwarf? Does it radiate enough heat and/or light to create its own biozone and is there a planet/planetoid in that range?