11885 Summanus

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]

11885 Summanus
Discovery [1]
Discovered bySpacewatch
Discovery siteKitt Peak Obs.
Discovery date25 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 arc20.54 yr (7,504 days)
Aphelion2.5119 AU
Perihelion0.8950 AU
1.7035 AU
Eccentricity0.4746
2.22 yr (812 days)
346.75°
0° 26m 35.88s / day
Inclination19.419°
359.89°
116.07°
Earth MOID0.0689 AU (26.8 LD)
Physical characteristics
Mean diameter
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 0.9–2.5 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 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 the Moon is about 0.0026 AU (390,000 km; 240,000 mi).

    References
    1. "11885 Summanus (1990 SS)". Minor Planet Center. Retrieved 2 November 2017.
    2. Noah Webster (1884) A Practical Dictionary of the English Language
    3. "JPL Small-Body Database Browser: 11885 Summanus (1990 SS)" (2011-04-12 last obs.). Jet Propulsion Laboratory. Retrieved 2 November 2017.
    4. "LCDB Data for (11885) Summanus". Asteroid Lightcurve Database (LCDB). Retrieved 2 November 2017.
    5. "Twentieth Anniversary of the First Automatic Discovery of a Near-Earth Asteroid by Software -- Spacewatch Project". Spacewatch. 25 September 2010. Archived from the original on 22 September 2015. Retrieved 9 June 2015.
    6. James V. Scotti (1993). Asteroids, Comets, Meteors 1993: Proceedings of the 160th Symposium of the International Astronomical Union, Held in Belgirate, Italy, June 14–18, 1993. Springer Science & Business Media (2012). p. 21. ISBN 9789401111485.
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