At the very edge of our solar system, scientists have discovered a new, extremely distant object billions of miles beyond Pluto. Because of its tiny size - just 300 kilometres across - it is far too faint to see for 99% of that time.
The world, estimated to have a width of a couple of hundred miles, is now about 7.4 billion miles from the sun, or about 2.5 times farther away than Pluto.
Scientists have confirmed a discovery made some three-years ago regarding a new dwarf planet on the edge of our Solar System which gives a fair bit of weight to the theory that a large, hidden ninth planet - the Planet X theory - exists somewhere in the deep reaches of space. Given its orbit, the Goblin never comes close enough to the giant planets in our solar system to be affected by their gravitational influence. Called either "Planet X" or "Planet Nine", this still-hypothetical world could remain undiscovered in much the same way The Goblin did.
"The more of them we can find, the better we can understand the outer Solar System and the possible planet that we think is shaping their orbits-a discovery that would redefine our knowledge of the solar system's evolution", Sheppard said.
"What makes this result really interesting is that Planet X seems to affect 2015 TG387 the same way as all the other extremely distant solar system objects", said researcher Chad Trujillo of Northern Arizona University.
"There are a lot of exotic and extreme objects yet to be found in the outer solar system", he says. "We are only seeing the tip of the ice berg", Sheppard said in an email.
The object's official name is 2015 TG38, but it's been nicknamed "The Goblin" because that's way cooler.
The astronomers have submitted a paper describing the discovery to The Astronomical Journal.
The object with the most-distant orbit at perihelion, 2012 VP113, was also discovered by Sheppard and Trujillo, who announced that find in 2014.
But the finding is also a reminder that we have a long way to go, "I think that with all of the exciting exoplanet discoveries in recent decades, people often lose sight of the fact that the only planet in our own solar system we could reliably detect around another star like the Sun is Jupiter".
The dwarf planet is about 190 miles in diameter based on preliminary measurements.
The gravity of big planets like Jupiter or Neptune can sling smaller objects into weird orbits if they happen to wander by. That would bring the number of true planets in our solar system back to nine, replacing Pluto which was demoted in 2006.
Dr Sheppard said: 'These so-called Inner Oort Cloud objects like 2015 TG387, 2012 VP113, and Sedna are isolated from most of the Solar System's known mass, which makes them immensely interesting. But that's all they can really say about The Goblin's physical characteristics. "These simulations do not prove that there's another massive planet in our Solar System, but they are further evidence that something big could be out there" Trujillo concludes. "These things have been twisted out of the solar system plane with help from Planet Nine and then scattered inward by Neptune". At TG387's most distant spot in its orbit, traveling there would be the equivalent to circling the earth seven times, or traveling three-quarters of the way to the moon.
The team will begin a new run of observations in November, with the hope of finding more objects, possibly including the elusive Planet Nine.