| Discovery[1] | |
|---|---|
| Discovered by | Spacewatch |
| Discovery site | Kitt Peak Obs. |
| Discovery date | 25 September 1990 |
| Designations | |
| 1990 SS | |
| Pronunciation | /sʌˈmeɪnəs/[2] |
Named after | Summānus |
| NEO · Apollo[3] | |
| Orbital characteristics[3] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 20.54 yr (7,504 days) |
| Aphelion | 2.5119AU |
| Perihelion | 0.8950 AU |
| 1.7035 AU | |
| Eccentricity | 0.4746 |
| 2.22yr (812 days) | |
| 346.75° | |
| 0° 26m 35.88s / day | |
| Inclination | 19.419° |
| 359.89° | |
| 116.07° | |
| Earth MOID | 0.0689 AU (26.8 LD) |
| Physical characteristics | |
| 1.298±0.446 km[3] | |
| 7.358 h[4] | |
| 0.033±0.029[3] | |
| 18.5[3] | |
11885 Summanus (prov. designation:1990 SS) is a darkasteroid and largenear-Earth object of theApollo group. It was discovered by astronomers with theSpacewatch programm atKitt Peak Observatory on 25 September 1990. The object has arotation period of 7.3 hours and measures approximately 1.3 kilometers (0.8 miles) in diameter.[3] It was named afterSummanus, the Roman deity of nocturnal lightning and thunder.[1]
Summanus was discovered on 25 September 1990, bySpacewatch survey at theKitt Peak Observatory, southwest of Tucson, Arizona, United States. It was the first fully automatic discovery of a near-Earth asteroid.[5][6] The nameSummanus is symbolic of the discovery of the asteroid by software running on a (lightning-fast) computer.[1]
The orbit is well-established with over 20 years of observations.Summanus orbits the Sun in theinner main-belt at a distance of 0.9–2.5 AU once every 2 years and 3 months (812 days). Its orbit has aneccentricity of 0.47 and aninclination of 19° with respect to theecliptic.[3]
The closest approach to the Earth in the years 1900–2200 is 0.102 AU (15,300,000 km; 9,500,000 mi) on 17 March 1991, and 17 March 2011. For comparison, the distance to theMoon is about 0.0026 AU (390,000 km; 240,000 mi).
