2018 AG37
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.
Preliminary orbit for 2018 AG37 | |
| Discovery | |
|---|---|
| Discovered by | |
| Discovery site | Mauna Kea Obs. |
| Discovery date | 15 January 2018 (first observed) |
| Designations | |
| 2018 AG37 | |
| "FarFarOut" (nickname) | |
| 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 |
| 80.2±4.5 AU | |
| Eccentricity | 0.655±0.02 |
| 717.8±60 yr | |
| 186.9°±219° | |
| 0° 0m 4.949s / day | |
| Inclination | 18.68°±0.12° |
| 68.35°±0.53° | |
| ≈2366? | |
| 231.9°±60° | |
| Neptune MOID | ≈3 AU (450 million km) |
| Physical characteristics | |
Mean diameter |
|
| 0.057 (est.) | |
| 25.3 | |
| |
At a very faint apparent magnitude of 25, only the largest telescopes in the world can observe it. Being so far from the Sun, 2018 AG37 moves very slowly among the background stars and has been observed only nine times in the first two years. It requires an observation arc of several years to refine the uncertainties in the approximately 700-year orbital period and determine whether it is currently near or at aphelion (farthest distance from the Sun). JPL Horizons computes an aphelion around the year 2005 at about 133 AU, whereas Project Pluto computes aphelion around the year 1976 slightly further out at 134 AU. Its perihelion is a little less than Neptune's.