Mysterious Object Orbits Abnormally Around the Sun -- Who is 'Niku'?
Our universe is full of mysterious objects, and the most recent of these is an object in a weird orbit beyond Neptune.
Discovered in August by astronomer Ying-Tung Chen of Academia Sinca in Taiwan and an international team of astronomers from Harvard to Hawaii to Germany, the retrograde trans-neptunian object (TNO) was named "Niku," which means "rebellious." As suggested by its name, the object moves in the opposite direction of nearly everything else in the solar system. Meaning, it is traveling upwards on a plane that is tiled to everything else.
According to their paper detailed in the arXiv, "Niku" was detected by the Pan-STARRS 1 (PS1) Outer Solar System Survey. Niku has been observed 22 times by PS1 at two different oppositions as well as the 1-m Lulin Observatory Telescope (LOT) in Taiwan.
Niku is an object with a diameter of about 124 and is 160,000 times fainter than Neptune. As mentioned by Space.com, Niku's orbit is inclined at an extreme 110-degree tilt with respect to the relatively thin, flat zone in which the eight major planets of the solar system orbit. Most TNOs are in much less inclined orbits, such as the 2008 KV42 (Drac), with 103.5 inclination.
Meanwhile, scientists can't figure out what's causing it to orbit the opposite way from the typical orbit.
Popular Mechanics cited some theories about Niku. One, is that a large object's gravity is influencing Niku's abnormal orbit -- Planet Nine, an unseen dwarf star called Nemesis, or an unknown dwarf planet in the Kuiper Belt. But the researchers deem the theories all problematic.
Furthermore, scientists speculated that there might exist more of objects like Niku, with similar inclined orbits beyond Neptune. Through their study, they have found out that indeed, there is an entire cluster (six objects) of similar objects is orbiting like Niku.
"They're not randomly distributed in the sky - they all seem to be aligned," study co-author Matthew Payne at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, told Space.com.
The scientists detailed their findings Oct. 17 at the American Astronomical Society Division for Planetary Sciences and European Planetary Science Congress in Pasadena, California and said that they are still conducting further studies about Niku and the other TNOs.