A diminutive Goblin lurks in the cold, dark recesses of the heavens, far past the icy blue depths of Poseidon, and even deeper into the void than the abode of Hades. And, according to the explorers that discovered this strange entity, the millennia-long journey into the abyss that this Goblin takes suggests that a resolution to an even deeper mystery — that of the elusive Planet Nine — may one day be solved.
This not-so-mythic "Goblin" is the newly discovered Trans-Neptunian object designated 2015 TG387, nicknamed "The Goblin" due to a combination of its discovery near Halloween, and its initials, "TG". The Goblin was discovered by astronomers Scott Sheppard from the Carnegie Institution for Science, Chad Trujillo from Northern Arizona University, and David Tholen from the University of Hawaii. The team was conducting a survey that was on the lookout for undiscovered Trans-Neptunian objects, including the elusive Planet Nine, using the Subaru 8-meter (26 foot) telescope at Mauna Kea, Hawaii in October of 2015.
The Goblin, a 300-kilometer (190-mile) dwarf planet, is currently only 80 astronomical units (AU) from the Sun; it comes as close as 65 AU, but plunges to over 2,000 AU into the depths of space at the farthest point of its 40,000-year orbit. An AU is the distance between the Earth and the Sun; to put 2015 TG387’s orbit in perspective, Pluto’s aphelion — its farthest point from the Sun — is 49 AU, only three-quarters of the distance to The Goblin’s closest approach.
Although very little is currently known about The Goblin’s nature, the eccentricity of its highly elliptical orbit, along with that orbit’s perihelion (closest point to the Sun) being clustered along with those of numerous other Trans-Neptunian objects, suggests that they are being shepherded by the hypothetical Planet Nine, a yet-to-be-discovered planet estimated to be ten times the mass of the Earth. Computer simulations run by The Goblin’s discoverers found that 2015 TG387’s orbit remained stable in the presence of such a planet, with the team announcing that there is an 85 percent chance that Planet Nine exists.