11885 Summanus
Near-Earth asteroid
From Wikipedia, the free encyclopedia
11885 Summanus (prov. designation: 1990 SS) is a dark asteroid and large near-Earth object of the Apollo group. It was discovered by astronomers with the Spacewatch programm at Kitt Peak Observatory on 25 September 1990. The object has a rotation period of 7.3 hours and measures approximately 1.3 kilometers (0.8 miles) in diameter.[3] It was named after Summanus, the Roman deity of nocturnal lightning and thunder.[1]
| Discovery[1] | |
|---|---|
| Discovered by | Spacewatch |
| Discovery site | Kitt Peak Obs. |
| Discovery date | 25 September 1990 |
| Designations | |
| 1990 SS | |
| Pronunciation | /sÊËmeɪnÉs/[2] |
Named after | SummÄnus |
| 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 | 2.5119 AU |
| Perihelion | 0.8950 AU |
| 1.7035 AU | |
| Eccentricity | 0.4746 |
| 2.22 yr (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] | |
Discovery and naming
Summanus was discovered on 25 September 1990, by Spacewatch survey at the Kitt Peak Observatory, southwest of Tucson, Arizona, United States. It was the first fully automatic discovery of a near-Earth asteroid.[5][6] The name Summanus is symbolic of the discovery of the asteroid by software running on a (lightning-fast) computer.[1]
Orbit
The orbit is well-established with over 20 years of observations. Summanus orbits the Sun in the inner main-belt at a distance of 0.9â2.5 AU once every 2 years and 3 months (812 days). Its orbit has an eccentricity of 0.47 and an inclination of 19° with respect to the ecliptic.[3]
The closest approach to the Earth in the years 1900â2200 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 the Moon is about 0.0026 AU (390,000 km; 240,000 mi).