New Dwarf Planet: Get Ready for More

The discovery of 2015 TG387, a new dwarf planet nicknamed “The Goblin”, was announced today. According to a Carnegie Institution for Science press release, this object’s closest approach to the sun (perihelion) is about 65 AU; a little more than double Pluto’s perihelion. However, its orbit is highly elliptical, and its aphelion is about 35x further. The story here fits into a puzzle about a hypothetical ninth planet in the far outer solar system.

The location in the sky where 2015 TG387 reaches perihelion is similar to 2012 VP113, Sedna, and most other known extremely distant trans-Neptunian objects, suggesting that something is pushing them into similar types of orbits.

The Goblin was discovered at about 80 AU, but it is not observable from Earth during most of its orbit. Instead of believing that this was complete luck, there is some suspicion that there’s a lot of extreme dwarf planets.

“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,” Tholen said. “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.”

Get ready for more!