Because there just might be a Planet X lurking well beyond Neptune.

Hey guys, Amy here for DNews.

Most of us grew up with nine planets.

Then Pluto became a dwarf planet along with the other Kuiper Belt objects and the layout

of our Solar System changed: Now we've got eight planets and hundreds of dwarf planets.

All of these objects orbit the Sun more or less regularly.

Their orbits are all slightly elliptical and vary in inclination, but lets call that regular.

Because there are objects beyond the Kuiper Belt that have extremely irregular orbits,

and they're throwing a bit of a wrench in how we imagine the Solar System is arranged.

Sedna is a dwarf planet that traces a highly elliptical orbit around the Sun.

1 Astronomical Unit, or AU is the distance from the Earth to the Sun.

Sedna only comes as close as 76 AU to the Sun and goes as far out as 940 AU.

And it's got a companion out there, a recently discovered dwarf planet called 2012 VP113

that only comes as close as 80 AU from the Sun and travels as away as 452 AU.

There are a small handful of other bodies with similarly strange orbits, and the question

plaguing astronomers is why: why are those bodies unlike all the other bodies?

They aren't part of a distant debris field, they're too far from Neptune to have their

orbits perturbed by Neptune, and they're too far from the Oort cloud.

It's possible a passing star pulled them away from the Kuiper Belt at some point.

Or it's possible there's a massive planet out there that not only pulled these objects

into their irregular orbits but is also keeping them in their strangely distant place.

It's far too early to tell — astronomers will need to make a lot more observations

to confirm anything — but studying the irregular orbits of these distant tiny worlds could

uncover the existence of a ninth planet in our solar system.

Or tenth, depending on your feelings about Pluto.

The discovery of 2012 VP113 is adding compelling evidence to this idea.

This isn't a new way of looking for planets.

It's actually how Neptune was discovered.

Neptune's orbit was predicted based on irregularities observed in Uranus' orbit; lo and behold the planet was there.

Irregularities in Neptune's orbit led to the prediction of an even more distant Planet X.

Pluto was actually found near this predicted planet but is too small to really act on Neptune.

So could the irregularities in these dwarf planets, when taken together, reveal a new

Planet X orbiting our Sun in our own cosmic backyard?

It might be a long shot, but it's not impossible!

So how do you guys feel about our ever-changing Solar System?

Let us know in the comments below or you can catch me on Twitter as @astVintageSpace.

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