If it exists. Right now, they're not quite sure:
The hunt is on for a gas giant up to four times the mass of Jupiter thought to be lurking in the outer Oort Cloud, the most remote region of the solar system. The orbit of Tyche (pronounced ty-kee), would be 15,000 times farther from the Sun than the Earth's, and 375 times farther than Pluto's, which is why it hasn't been seen so far.Stay tuned! Breaking!
But scientists now believe the proof of its existence has already been gathered by a Nasa space telescope, Wise, and is just waiting to be analysed.
The first tranche of data is to be released in April, and astrophysicists John Matese and Daniel Whitmire from the University of Louisiana at Lafayette think it will reveal Tyche within two years.
And of course, those spoilsport scientists may find away to make this not a planet too:
Whether it would become the new ninth planet would be decided by the International Astronomical Union (IAU). The main argument against is that Tyche probably formed around another star and was later captured by the Sun's gravitational field. The IAU may choose to create a whole new category for Tyche, Professor Matese said.Jeeze, waddya want? Pluto's too small, Tyche's an illegal immigrant...
Here's an image the Independent did (link to the original pdf) showing where Tyche would be (if it exists -- again, still not proven):
Wildly cool, says I.