The small club of known dwarf planets orbiting our sun, which controversially includes Pluto, has just added another member.
The International Astronomical Union’s Minor Planet Center announced Oct. 2 that researchers have discovered a new dwarf planet, 2015 TG387, that is roughly 186 miles across and likely made of ice. Owing to its discovery near Halloween on Oct. 13, 2015, the research team nicknamed the new object "the Goblin."
"We think there could be thousands of small bodies like 2015 TG387 out on the Solar System’s fringes, but their distance makes finding them very difficult," David Tholen, an astronomer at the University of Hawaii, said in a press release.
The fact that the research team was able to spot Goblin at all is matter of perfect celestial timing. The dwarf planet features an extremely elongated orbit that varies from 65 AU (over 6 billion miles from the sun) to more than 2,300 AU (213 billion miles from the sun). To complete one orbit, it takes an astounding 40,000 years. To put that in perspective, the last time humanity would have had a shot at glimpsing the Goblin, cave painting was in vogue.
"Currently we would only detect 2015 TG387 when it is near its closest approach to the Sun," added Tholen. "For some 99 percent of its 40,000-year orbit, it would be too faint to see."
Should 2015 TG387 be officially recognized, it would join five other officially recognized dwarf planets in our solar system: Pluto, Ceres, Eris, Makemake and Haumea.
More evidence of a mysterious Planet X?
An illustration of the mysterious Planet X, a super-Earth-sized planetary body that may exist in the farthest reaches of our solar system. (Photo: Roberto Mola rCandanosa/Scott Shppard/Carnegie Institution for Science, DTM)
The discovery of the new dwarf planet is part of an ongoing effort by Tholen and his colleagues –– Carnegie Institution for Sciences's Scott Sheppard and Northern Arizona University’s Chad Trujillo –– to not only unmask distant solar system objects, but also the elusive Planet X. Similar to other recently discovered dwarf planets "Sedna" and "2012VP113," the orbit of the Goblin may be influenced by a larger planetary body orbiting hundreds of AUs from the sun. When researchers inserted a super-earth-mass planet into a simulation relative to the extreme distance of the other dwarf planets, they noticed a kind of "gravitational shepherding" that kept the objects from approaching Planet X too closely.
"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," Trujillo said. "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."
Present estimates are that as many as 200 new dwarf planets may be discovered in the coming years as surveys of the extreme farthest reaches of our solar system advance.
"These distant objects are like breadcrumbs leading us to Planet X," said Sheppard, whose team will begin a new round of observations in November. "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."