spaceSpace and Physics

Astronomers Have Discovered A Mysterious New World At The Edge Of The Solar System


Dr. Alfredo Carpineti

Senior Staff Writer & Space Correspondent

clockOct 2 2018, 15:00 UTC

Artist’s  impression of Planet  Nine.  Roberto  Molar  Candanosa/ Scott  Sheppard/  Carnegie  Institution  for  Science

A new trans-Neptunian object has been discovered by astronomers in the search for a hypothetical massive planet far beyond the orbit of Neptune. The small body is called 2015 TG387 (nicknamed "The Goblin") and is currently 80 times further from the Sun than Earth is, truly at the edge of the known Solar System.

The announcement was made by the International Astronomical Union’s Minor Planet Center and information about the object is reported in The Astronomical Journal. The object's closest approach to the Sun, its perihelion, is about 65 astronomical units (AU), where 1 AU is the Earth-Sun distance. Only two other bodies in the Solar System have a more distant perihelion, planetoid 2012 VP113 and dwarf planet Sedna. But 2015 TG387 has a more eccentric orbit going further away from the Sun.


“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,” co-author David Tholen, from the University of Hawaii, said in a statement. “Currently we would only detect 2015 TG387 when it is near its closest approach to the Sun. For some 99 percent of its 40,000-year orbit, it would be too faint to see.”

The orbits of the new extreme dwarf planet 2015 TG387 and its fellow Inner Oort Cloud objects 2012 VP113 and Sedna as compared with the rest of the Solar System. R Molar Candanosa /S. Sheppard / Carnegie Institution for Science.

The orbits of these small trans-Neptunian objects have similar peculiarities. They all reach the perihelion roughly at the same point in the sky. This had researchers suspecting that something is influencing these objects and over the last few years the idea of Planet Nine or planet X came about. There could be a massive planet hundreds of AU away from the Sun.  

“These distant objects are like breadcrumbs leading us to Planet X. 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,” co-author Scott Sheppard, from the Carnegie Institution for Science, added.

“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. They can be used as probes to understand what is happening at the edge of our Solar System.”


There is no conclusive evidence that Planet Nine is out there but simulation showed that its presence would guarantee the stability of 2015 TG387's orbit for as long as the Solar System has existed. The evidence for Planet Nine remains circumstantial but if it’s out there we are getting closer to it.

The images of 2015 TG387 turned into a gif to show the object moving in the sky. S. Sheppard

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