What was Planet X about?

Question

What was Planet X?

Answer 1

One reason

Planet X used to be Pluto, Space and nasa created a name for this planet, until, I think a girl just came up with some name called Pluto, nasa thought it was interesting, the name soon replaced Planet X.

Second Reason: Either its that or either Planet X is another planet which I doubt it.

Third Reason: It may be a myth, or not true at all, people just say about it.

Answer 2

Planet X was first Neptune then it became Pluto and now they are still looking for a Planet X witch is supposes to be a large as Jupiter or a brown/red dwarf star.

Answer 3

I think:  Pluto is named NOT because of a girl.  Planets have names of gods and goddesses and pluto is the god of the underworld.  Planet x was discovered using keplers laws saying that a planet should be this distance and another should be at that distance and so on.  But the kept finding objects like pluto and planet x out near pluto's orbit.  hence why they had a meeting and now call pluto a keiper belt object or plutonian object. planet x was going to be number ten. roman numeral x = 10.

Answer 4

There are three distinct planet x.

1.  A planet (yet undiscovered) that should exist beyond the orbit of Neptune.  In the late 1800s, astronomers thought that there was another planet beyond Neptune, because they thought that Neptune's orbit was (ever so slightly) different than what is should be.

The search for that planet x led to the discovery of Pluto.

Since then, we found out that Pluto is much smaller than first thought (it cannot be responsible for any perturbation in Neptune's orbit), AND we found that the "perturbations" were really uncertainties in the calculations.

However, with the recent discoveries of other dwarf planets beyond Pluto, statistical analysis tells us that there is a good probability that we will, one day, find something out there that is the size of a real planet.  That is the modern Planet X.  

If it exists (it is only a statistical probability for now), then it would be on a relatively stable orbit (otherwise, we would have already seen large perturbations in the Kuyper belt objects -- and we haven't).

1 1/2 (one and a half): In the late 1990s, with the discovery of the first Trans Neptunian Object bigger than Pluto, this object was proposed as the 10th planet for the solar system.  It was called Planet X, where the X, in this instance, meant the Roman numeral "10".

2.  Planet X is also a convenient label for observations of probable planets around other stars, until they are confirmed (and then given an official name/number) or disproved (then they are simply dropped).  These are so far away that they will never, ever come close to our solar system.

Ever.

3.  The label "Planet X" has been used by charlatans participating in the Big 2012 Hoax Off.  They started off by using the name "Nibiru" but I guess they got tired of being told by everyone that we already knew that Nibiru (in that context) is a fictitious planet.  Even the guy who invented it is tired of seeing how "his" fictitious planet is being forced to participate in the Big 2012 Hoax Off.

So, they changed the name to "Planet X".  It makes it sound ominous.  Plus, it has the advantage that you can use things like "Even NASA talks of planet X" (except that NASA uses the definition of number 1, above).