Science & Technology

There's a New World Beyond Pluto That Astronomers Have Named "The Goblin"

While searching for evidence of a huge planet lurking beyond Pluto's orbit dubbed "Planet Nine," astronomers made a surprise discovery: a previously undetected dwarf planet flying through the darkness. They've nicknamed it "the Goblin," and this little world could help us uncover the secret of the much larger Planet Nine.

An artist’s conception of a distant Solar System Planet Nine, which could be shaping the orbits of smaller extremely distant outer Solar System objects like 2015 TG387 discovered by a team of Carnegie’s Scott Sheppard, Northern Arizona University’s Chad Trujillo, and the University of Hawaii’s David Tholen.

What is Planet Nine, Anyway?

In 2016, astronomers hypothesized there must be a roughly Neptune-sized world far, far away in the solar system that's perturbing the orbits of nearby space rocks. They called this world "Planet Nine." Astronomers all over Earth are searching for this distant exoplanet. So far, Planet Nine remains hidden, if it's there at all.

But remember, space is a big place and it could take years and years of searching to confirm the existence of Planet Nine. In the meantime, the quest yielded another tiny world in the blackness of space. It's called 2015 TG387, but astronomers were inspired by the "TG" to nickname it "the Goblin."

The little world is in a remarkable place. It orbits the sun some 80 times further away than Earth, and it takes 40,000 years to complete a single orbit. Let's put it this way: The last time the Goblin was at this point in its path around the sun, there were still other species of human on Earth, and they were millennia away from inventing civilization. Let alone telescopes. Or even spacecraft. We're incredibly lucky we spotted this world before its warped orbit sends it even further away from Earth, where it would be even harder 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. 2015 TG387 was nicknamed “The Goblin” by the discoverers, as its provisional designation contains TG and the object was first seen near Halloween. 2015 TG387 has a larger semi-major axis than either 2012 VP113 or Sedna, which means it travels much further from the Sun at its most distant point in its orbit, which is around 2300 AU.
A comparison of 2015 TG387 at 65 AU with the Solar System’s known planets. Saturn can be seen at 10 AU and Earth is, of course, at 1 AU, as the measurement is defined as the distance between the Sun and our home planet.

Evidence for Planet Nine Piles up

And how is the new world relevant to Planet Nine? Well, astronomers ran some simulations of the Goblin while assuming a Neptune-sized or super-Earth-sized planet was also out there. Long story short, it looks like if Planet Nine did exist, it actually shepherded the Goblin along its orbit. In fact, Planet Nine's gravitational influence might keep a bunch of distant worlds far away from it, which would avoid the chance of a nasty collision.

Here's where things get really intriguing. The newly discovered world is far away from us, but it isn't alone in its neighborhood. There are other dwarf planets in that zone, called Sedna and 2012 VP113. These little worlds all travel in their own zone far away from the main mass of our solar system, where all the planets reside (you know, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune). Taken together, the orbits of these dwarf worlds could be a powerful argument that Planet Nine is a real thing.

This orbital situation "makes them [the dwarf worlds] immensely interesting" because "they can be used as probes to understand what is happening at the edge of our solar system," said lead author Scott Sheppard of the Carnegie Institution for Science in a statement.

One caveat: The paper on the Goblin's discovery has not been published yet in a peer-reviewed journal, which is considered the gold standard of science because other scientists verify the work before publication. That said, the Astronomical Journal is considering the paper's submission.

And let's remember what Sheppard and colleagues announced earlier this year, again while searching for the elusive Planet Nine: 12 new moons around the planet Jupiter. So the search for this theoretical planet already bore scientific fruit. We can't wait to see what happens next.

Get stories like this one in your inbox each morning. Sign up for our daily email here.

Why isn't Pluto a planet anymore? Get to the bottom of it from the "Pluto killer" himself with Neil deGrasse Tyson's book "The Pluto Files: The Rise and Fall of America's Favorite Planet." We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Elizabeth Howell October 2, 2018

Curiosity uses cookies to improve site performance, for analytics and for advertising. By continuing to use our site, you accept our use of cookies, our Privacy Policy and Terms of Use.