2018 AG₃₇

2018 AG₃₇
	2018 AG37 imaged by the Gemini North telescope in May 2019
Discovery
Discovered by	S. S. Sheppard; D. J. Tholen; C. Trujillo;
Discovery site	Mauna Kea Obs.
Discovery date	15 January 2018; (first observed)
Designations
MPC designation	2018 AG37
Alternative designations	"FarFarOut" (nickname)
Minor planet category	SDO; TNO; distant; centaur;
Orbital characteristics
	Epoch 2019-Feb-26 (JD 2458540.5)
	Uncertainty parameter 9
Observation arc	2.03 yr (740 days) using 11 observations
Aphelion	132.7±7.4 AU
Perihelion	27.63±0.17 AU
Semi-major axis	80.2±4.5 AU
Eccentricity	0.655±0.02
Orbital period (sidereal)	717.8±60 yr
Mean anomaly	186.9°±219°
Mean motion	0° 0m 4.949s / day
Inclination	18.68°±0.12°
Longitude of ascending node	68.35°±0.53°
Time of perihelion	≈2366?
Argument of perihelion	231.9°±60°
Known satellites	0
Neptune MOID	≈3 AU (450 million km)
Physical characteristics
Mean diameter	≈400 km (est.)
Apparent magnitude	25.3
Absolute magnitude (H)	4.22±0.10; 4.22;

2018 AG₃₇ is a distant trans-Neptunian object and centaur that was discovered 132.2 ± 1.5 AU (19.78 ± 0.22 billion km) from the Sun, farther than any other currently observable known object in the Solar System. Imaged in January 2018 during a search for the hypothetical Planet Nine, the confirmation of this object was announced in a press release in February 2021 by astronomers Scott Sheppard, David Tholen, and Chad Trujillo. The object was nicknamed "FarFarOut" to emphasize its distance from the Sun. 2018 AG₃₇ was discovered when it was near aphelion, the farthest point from the Sun in its elliptical orbit. The object is estimated to be at least 400 km (250 mi) in diameter. Because of its extreme distance, 2018 AG₃₇ appears extremely faint with an apparent magnitude of 25—only visible to the largest telescopes in the world.