| Minorplanet: | yes |
| (20161) | |
| Background: |
|
| Discovered: | 8 October 1996 |
| Epoch: | 4 September 2017 (JD 2458000.5) |
| Uncertainty: | 4 |
| Observation Arc: | 12.04 yr (4,398 days) |
| Perihelion: | 28.630 AU |
| Semimajor: | 47.621 AU |
| Eccentricity: | 0.3988 |
| Period: | 328.63 yr (120,032 d) |
| Mean Motion: | / day |
| Inclination: | 12.436° |
| Asc Node: | 343.11° |
| Arg Peri: | 308.70° |
| Dimensions: | 139 km |
| Abs Magnitude: | 7.5 |
is a trans-Neptunian object orbiting beyond Pluto in the Kuiper belt of the outermost Solar System, approximately 139km (86miles) in diameter. It was discovered on 8 October 1996, by astronomers David Jewitt, Chad Trujillo, Jane Luu, and Jun Chen at the Mauna Kea Observatory, Hawaii, in the United States. It was the first discovery of a twotino.
It orbits the Sun at a distance of 28.6–66.6 AU once every 328 years and 8 months (120,032 days). Its orbit has an eccentricity of 0.40 and an inclination of 12° with respect to the ecliptic. Near perihelion, it comes closer to the Sun than Neptune does (29.7 AU). It has a semi-major axis (average distance from the Sun) near the edge of the classical belt.
was the first twotino discovered. Twotinos stay in a 1:2 orbital resonance with Neptune, which means that for every one orbit a twotino makes, Neptune orbits two times. Both the Minor Planet Center and the Deep Ecliptic Survey list this trans-Neptunian object as a twotino.
This minor planet was numbered by the Minor Planet Center on 9 January 2001. As of 2018, it has not been named.