From liquid-filled canyons on Io to super-sized meteor showers, this year has been full of fascinating news about our solar system. Now, a new discovery has scientists scratching their heads in wonder about what might lie at the edge of our cosmic neighborhood. A mysterious object was detected just past Neptune, and astronomers are unsure what gave it its unique properties.

An international team of astronomers researching the object has published the results of their study, which are still awaiting peer review. The newfound trans-Neptunian object is presumed to be a dwarf planet, and scientists have named it Niku. Based on its brightness, Niku is thought to be less than 200km in diameter. Several other dwarf planets and planetoids have been found recently near or beyond Neptune, and Niku was assumed to be similar to them. However, astronomers got a real treat when they began to observe and study Niku’s behaviors.

Niku's orbit sends it far beyond Neptune.

The mystery surrounding Niku stems from its strange orbit. While most objects orbit the Sun in the same direction as the Sun rotates, Niku orbits in the opposite direction. Furthermore, Niku orbits the Sun on a plane that is tilted 110 degrees off of the plane upon which the rest of the planets orbit. While other objects have been found that orbit the Sun in the opposite direction, the combination of these two facts is curious, to say the least.

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Niku’s orbit is tilted 110 degrees to the orbit of the rest of the planets in our solar system.

As of now, scientists are unsure what to make of Niku’s unique orbit or how to explain it. Michele Bannister, an astronomer at Queens University Belfast, told New Scientist that the mystery of Niku makes it a prime subject for future study:

It’s wonderful that it’s so confusing. I’m looking forward to seeing what the theoretical analysts do once they get their hands on this one.

When solar systems form, the angular momentum, or spin, of forming stars create gas clouds spinning outwards from their centers; all the planets in our solar system orbit in the same direction due to the spin of our Sun as it formed. The unusual orientation and direction of Niku’s orbit thus imply that some cosmic event or object set it on its unusual course at some point in the past. What this might have been remains a mystery.

Brett Tingley

Brett Tingley is a writer and musician living in the ancient Appalachian mountains.

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