(471325) 2011 KT19

(471325) 2011 KT₁₉
Discovery
Discovered by	Mount Lemmon Srvy.; List Ying-Tung Chen; Hsing Wen Lin; Matthew J. Holman; Matthew J. Payne; Wesley C. Fraser; Pedro Lacerda; Wing-Huen Ip; Wen-Ping Chen; Rolf-Peter Kudritzki; Robert Jedicke; Richard J. Wainscoat; John L. Tonry; Eugene A. Magnier; Christopher Waters; Nick Kaiser; Shiang-Yu Wang; Matthew Lehner; ;
Discovery site	Mount Lemmon Obs.
Discovery date	31 May 2011
Designations
Pronunciation	/ˈniːkuː/
Named after	A Chinese adjective meaning "rebellious"
Alternative designations	Niku
Minor planet category	TNO · centaur; damocloid
Orbital characteristics
	Epoch JD 2457600.5
	Uncertainty parameter 2
Observation arc	1779 days (4.87 yr)
Aphelion	47.427 AU
Perihelion	23.7805 AU
Semi-major axis	35.604 AU
Eccentricity	0.33208
Orbital period (sidereal)	212.45 years
Mean anomaly	29.487°
Inclination	110.1537°
Longitude of ascending node	243.77772°
Argument of perihelion	322.174°
TJupiter	−1.552
Physical characteristics
Mean diameter	75–250 km; 161 km
Apparent magnitude	22
Absolute magnitude (H)	7.2

(471325) 2011 KT₁₉, nicknamed Niku (/niːkuː/), is a trans-Neptunian object whose orbit is tilted 110° with respect to the planets' orbital plane. Thus, it has a nearly polar retrograde orbit around the Sun.^[2]^[7]^[8]^[9]

While the object has not received a formal name, it received the moniker "Niku" (逆骨), meaning "rebellious" in the Chinese language, by its discoverers.^[10]^[11]

^ Cite error: The named reference MPEC2011-L09 was invoked but never defined (see the help page).
^ ^a ^b "Mystery object in weird orbit beyond Neptune cannot be explained". New Scientist. 10 August 2016. Archived from the original on 11 August 2016. Retrieved 11 August 2016.
^ ^a ^b ^c Cite error: The named reference jplorbit was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference johnstonsarchive-TNO-list was invoked but never defined (see the help page).
^ ^a ^b "IAU Minor Planet Center - 2011 KT19". Minor Planet Center. IAU. Retrieved 12 August 2016.
^ "AstDyS (471325) 2011KT19 Ephemerides". Retrieved 18 February 2017.
^ Chen, Ying-Tung; Lin, Hsing Wen; Holman, Matthew J; Payne, Matthew J; et al. (5 August 2016). "Discovery of A New Retrograde Trans-Neptunian Object: Hint of A Common Orbital Plane for Low Semi-Major Axis, High Inclination TNOs and Centaurs". The Astrophysical Journal. 827 (2): L24. arXiv:1608.01808. Bibcode:2016ApJ...827L..24C. doi:10.3847/2041-8205/827/2/L24. S2CID 4975180.
^ Charles Q. Choi (2016-10-24). "What's Up with 'Niku'? Object's Weird Orbit Puzzles Scientists". Space.com. Retrieved 2022-12-21.
^ "What Makes the Solar System Like a Crime Scene? - Science Friday". 19 August 2016. Retrieved 19 August 2016.
^ Grossman, David (11 August 2016). "Meet Niku, the Weird Object Beyond Neptune That Nobody Can Figure Out". Popular Mechanics. Retrieved 21 December 2021.
^ Choi, Charles Q. (24 October 2016). "What's Up with 'Niku'? Object's Weird Orbit Puzzles Scientists". Space.com. Retrieved 21 December 2021.

[MPEC2011-L09-1] Cite error: The named reference MPEC2011-L09 was invoked but never defined (see the help page).

[newscientist-2] "Mystery object in weird orbit beyond Neptune cannot be explained". New Scientist. 10 August 2016. Archived from the original on 11 August 2016. Retrieved 11 August 2016.

[jplorbit-3] Cite error: The named reference jplorbit was invoked but never defined (see the help page).

[johnstonsarchive-TNO-list-4] Cite error: The named reference johnstonsarchive-TNO-list was invoked but never defined (see the help page).

[mpcorbit-5] "IAU Minor Planet Center - 2011 KT19". Minor Planet Center. IAU. Retrieved 12 August 2016.

[AstDyS-6] "AstDyS (471325) 2011KT19 Ephemerides". Retrieved 18 February 2017.

[arxiv5aug-7] Chen, Ying-Tung; Lin, Hsing Wen; Holman, Matthew J; Payne, Matthew J; et al. (5 August 2016). "Discovery of A New Retrograde Trans-Neptunian Object: Hint of A Common Orbital Plane for Low Semi-Major Axis, High Inclination TNOs and Centaurs". The Astrophysical Journal. 827 (2): L24. arXiv:1608.01808. Bibcode:2016ApJ...827L..24C. doi:10.3847/2041-8205/827/2/L24. S2CID 4975180.

[8] Charles Q. Choi (2016-10-24). "What's Up with 'Niku'? Object's Weird Orbit Puzzles Scientists". Space.com. Retrieved 2022-12-21.

[9] "What Makes the Solar System Like a Crime Scene? - Science Friday". 19 August 2016. Retrieved 19 August 2016.

[10] Grossman, David (11 August 2016). "Meet Niku, the Weird Object Beyond Neptune That Nobody Can Figure Out". Popular Mechanics. Retrieved 21 December 2021.

[11] Choi, Charles Q. (24 October 2016). "What's Up with 'Niku'? Object's Weird Orbit Puzzles Scientists". Space.com. Retrieved 21 December 2021.

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Discovery^[1]
Discovered by	Mount Lemmon Srvy. List Ying-Tung Chen Hsing Wen Lin Matthew J. Holman Matthew J. Payne Wesley C. Fraser Pedro Lacerda Wing-Huen Ip Wen-Ping Chen Rolf-Peter Kudritzki Robert Jedicke Richard J. Wainscoat John L. Tonry Eugene A. Magnier Christopher Waters Nick Kaiser Shiang-Yu Wang Matthew Lehner
Discovery site	Mount Lemmon Obs.
Discovery date	31 May 2011
Designations
Pronunciation	/ˈniːkuː/
Named after	A Chinese adjective meaning "rebellious" ^[2]
Alternative designations	Niku
Minor planet category	TNO^[3] · centaur^[4] damocloid
Orbital characteristics^[3]
Epoch JD 2457600.5
Uncertainty parameter 2
Observation arc	1779 days (4.87 yr)
Aphelion	47.427 AU
Perihelion	23.7805 AU
Semi-major axis	35.604 AU
Eccentricity	0.33208
Orbital period (sidereal)	212.45 years
Mean anomaly	29.487°
Inclination	110.1537°
Longitude of ascending node	243.77772°
Argument of perihelion	322.174°
T_Jupiter	−1.552
Physical characteristics
Mean diameter	75–250 km^[5] 161 km^[4]
Apparent magnitude	22^[6]
Absolute magnitude (H)	7.2^[5]^[3]