Planet X: In Hunt for Theoretical Orb, "the Goblin" Is Discovered Instead

Ever since Pluto was demoted to dwarf planet status, we’ve poured salt into its wounds by searching for actual planets even farther beyond it. Most vivid in the public’s minds is the compellingly named “Planet X,” a hypothetical object at the far reaches of our solar system that some scientists believe tugs on the orbits of the other planets within it. During a recent hunt for this hypothetical planet, scientists failed to discover Planet X itself — but found something else that supports its existence.

As the astronomers from the Carnegie Institute of Science, Northern Arizona University, and University of Hawaii announced on Tuesday, the recent hunt for Planet X led to the discovery of 2015 TG387, an object two and a half times farther away from the Sun than Pluto currently is. This extreme dwarf planet — nicknamed “The Goblin” because it was first spotted around Halloween — supports the idea that Planet X is out there, somewhere even farther out, the scientists write in their preprint, which has been submitted to The Astronomical Journal.

“These distant objects are like breadcrumbs leading us to Planet X,” said Scott Sheppard, Ph.D., lead author and Carnegie staff scientist. “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.”

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. 

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; line-height: 12.0px; font: 12.0px Calibri; -webkit-text-stroke: #000000} span.s1 {font-kerning: none} Illustration  by  Roberto  Molar  Candanosa  and  Scott  Sheppard,  courtesy  of  Carnegie  Institution  for  Science. 

Though Planet X (sometimes, confusingly, also referred to as “Planet Nine”) is accepted by NASA as a hypothetical planet, there’s still a lot of uncertainty surrounding its existence. As NASA writes:

The existence of this distant world is only theoretical at this point and no direct observation of the object nicknamed have been made. The mathematical prediction of a planet could explain the unique orbits of some smaller objects in the Kuiper Belt, a distant region of icy debris that extends far beyond the orbit of Neptune. Astronomers are now searching for the predicted planet.

In the new paper, the astronomers show that The Goblin could be one of many objects with extra-long orbits that circles the solar system far beyond its accepted borders. Its perihelion — the point at which it’s closest to the Sun — is the third-most distant one scientists are aware of (two others are two objects like The Goblin, also discovered by Sheppard and co-author Chad Trujillo, Ph.D., from Northern Arizona University). In other words, this dwarf planet is one of the farthest objects we’re aware of that orbits our sun.

Here's how the Goblin matches up with the other objects in the Solar System. It's far out!

Illustration  by  Roberto  Molar  Candanosa  and  Scott  Sheppard,  courtesy  of  Carnegie  Institution  for  Science. 

The Goblin, however, has a weird, non-circular orbit that takes it much farther away from the Sun than its Inner Oort Cloud peers — up to 2,300 astronomical units at its farthest point. Because these objects are so far away from the bulk of the Solar System yet still are part of it, explains Sheppard, the “can be used as probes to understand what is happening at the edge of our Solar System.”

Using computer modeling, the team used what they know about The Goblin’s orbit to test the effect of different hypothetical Planet X orbits on the movement of object around it. In their simulations, they found that the existence of a Planet X is consistent with the known orbit of The Goblin, which is likely “shepherded” — along with other Inner Oort Cloud objects — by Planet X’s gravitational pull.

What this new discovery is not, it should be pointed out, is Nibiru, the fictional planet that some conspiracy theorists have conflated with the hypothetical Planet X/Planet Nine and is rumored by some to be hurtling toward Earth. The Goblin is far from that, but in its own way, having lurked undetected at the distant reaches of our solar system for so long, it’s just as spooky.

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