Mysterious object discovered in strange orbit beyond Neptune

Sometimes you read a headline and think: That's the kind of article that'd be in a tattered newspaper flapping past a destroyed playground in "The Terminator." Juuuust creepy enough that it could be either completely innocent, or portending an end-of-the-world-as-we-know-it disaster. (Why IS that Rio swimming pool green?)
Here's another one: There's a mystery object in a weird orbit beyond Neptune that can't be explained, New Scientist reports. And this tweet, from Belfast astronomer Michele Bannister, didn't help my nerves. ("TNO" means Trans-Neptunian Object, and also could be a neat sequel to "E.T.")

The object has been nicknamed "Niku," after the Chinese term for "rebellious," because its weird orbit means it's swinging around the sun backward. (Niku, you little rebel! Take off those headphones, clean your room and start orbiting forward before I pull this planet over!)

In order for it to be orbiting backward, Niku must have been knocked off course by something unknown, New Scientist reports. And that's what gets astronomers up in the morning. They've already tested to see if its goofy orbit could be related to the gravitational pull of what's called Planet Nine, and decided that's not the case.
The orbit "suggests that there's more going on in the outer solar system than we're fully aware of," said Matthew Holman, part of the team that discovered Niku.
That lonely stretch of space out past Neptune was in the news just last month, when a new dwarf planet, called 2015 RR245 for now, was discovered. I'll start paying attention to that when it gets its own cool nickname.