128 Nemesis
From Wikipedia, the free encyclopedia
For other uses, see Nemesis (disambiguation).
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Discovery[1]
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| Discovered by | James Craig Watson |
| Discovery date | November 25, 1872 |
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Designations
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| Named after | Nemesis |
| Alternate name(s) | |
| Minor planet category |
Main belt[1] |
| Epoch December 31, 2006 (JD 2454100.5) | |
| Aphelion | 463.605 Gm (3.099 AU) |
| Perihelion | 359.010 Gm (2.400 AU) |
| Semi-major axis | 411.307 Gm (2.749 AU) |
| Eccentricity | 0.127 |
| Orbital period | 1665.175 d (4.56 a) |
| Average orbital speed | 17.89 km/s |
| Mean anomaly | 181.168° |
| Inclination | 6.254° |
| Longitude of ascending node | 76.457° |
| Argument of perihelion | 302.407° |
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Physical characteristics
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| Dimensions | 188.16 km[1] |
| Mass | 7.0×1018 kg |
| Mean density | ? g/cm³ |
| Equatorial surface gravity | 0.0526 m/s² |
| Escape velocity | 0.0995 km/s |
| Rotation period | 39 hr[1] |
| Albedo | 0.05[1] |
| Temperature | ~168 K |
| Spectral type | C[1] |
| Apparent magnitude | 10.46 to 13.58 |
| Absolute magnitude (H) | 7.49[1] |
128 Nemesis is a large 188km main-belt asteroid, of carbonaceous composition. It rotates rather slowly, taking about one and half Earth days (39 hours)[1] to complete one revolution. Nemesis is the largest member of the Nemesian asteroid family bearing its name. It was discovered by J. C. Watson on November 25, 1872,[1] and named after Nemesis, the goddess of retribution in Greek mythology. Nemesis is also the name of a hypothetical companion star of the Sun.
Based on IRAS data Nemesis is about 188km in diameter and is around the 33rd largest main-belt asteroid.[2]
[edit] References
- ^ a b c d e f g h i "JPL Small-Body Database Browser: 128 Nemesis". Jet Propulsion Laboratory. 2011-06-13 last obs (arc=138 years). http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=Nemesis. Retrieved 2011-12-06.
- ^ "JPL Small-Body Database Search Engine: asteroids and orbital class (IMB or MBA or OMB) and diameter > 188.1 (km)". JPL's Solar System Dynamics Group. http://ssd.jpl.nasa.gov/sbdb_query.cgi?obj_group=all;obj_kind=ast;obj_numbered=all;ast_orbit_class=IMB;ast_orbit_class=MBA;ast_orbit_class=OMB;OBJ_field=0;ORB_field=0;c1_group=OBJ;c1_item=Ap;c1_op=%3E;c1_value=188.1;table_format=HTML;max_rows=500;format_option=comp;c_fields=AcApAiBhBgBjBkBlBiBnBs;.cgifields=format_option;.cgifields=obj_kind;.cgifields=obj_group;.cgifields=obj_numbered;.cgifields=ast_orbit_class;.cgifields=table_format;.cgifields=com_orbit_class&query=1&c_sort=ApA. Retrieved 2012-04-17.
[edit] External links
- Orbital simulation from JPL (Java) / Ephemeris
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