128 Nemesis is a large 180 km

main-belt The asteroid belt is a torus-shaped region in the Solar System, centered on the Sun and roughly spanning the space between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies called asteroids ...

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

, of

carbonaceous Carbonaceous refers to something relating to, containing, or composed of carbon. It is a descriptor used for the attribute of any substance rich in carbon. Particularly, ''carbonaceous hydrocarbons'' are very unsaturated, high- molecular-weight h ...

composition. It rotates rather slowly, taking about 78 hours to complete one rotation. Nemesis is the largest member of the Nemesian asteroid family bearing its name. It was discovered by J. C. Watson on 25 November 1872, and named after

Nemesis In ancient Greek religion and myth, Nemesis (; ) also called Rhamnousia (or Rhamnusia; ), was the goddess who personified retribution for the sin of hubris: arrogance before the gods. Etymology The name ''Nemesis'' is derived from the Greek ...

, the goddess of retribution in

Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...

. left, Diagram of Nemesis's orbit This object is orbiting the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

with a

period Period may refer to: Common uses * Period (punctuation) * Era, a length or span of time *Menstruation, commonly referred to as a "period" Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (o ...

of and an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

(ovalness) of 0.13. The

orbital plane The orbital plane of a revolving body is the geometric plane in which its orbit lies. Three non-collinear points in space suffice to determine an orbital plane. A common example would be the positions of the centers of a massive body (host) a ...

is inclined by 6.2° to the

plane of the ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. From the perspe ...

. It is categorized as a

C-type asteroid C-type (carbonaceous ) asteroids are the most common variety, forming around 75% of known asteroids. They are volatile-rich and distinguished by a very low albedo because their composition includes a large amount of carbon, in addition to rocks ...

, indicating a primitive

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

aceous composition. Based on

IRAS The Infrared Astronomical Satellite (Dutch language, Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a astronomical survey, survey of the entire night sky at infrared wavelengths. Launched on 25 Janu ...

data Nemesis is about 188 km in diameter and is around the 33rd largest

asteroid, while WISE measurements yield a size of ~163 km. The 77.81‑hour

rotation period In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...

is the second longest for an asteroid more than 150 km in diameter. Between 2005 and 2021, 128 Nemesis has been observed to

occult The occult () is a category of esoteric or supernatural beliefs and practices which generally fall outside the scope of organized religion and science, encompassing phenomena involving a 'hidden' or 'secret' agency, such as magic and mysti ...

eight stars.

Notes

References

External links

* * * {{DEFAULTSORT:Nemesis 000128 Discoveries by James Craig Watson Named minor planets 000128 000128 18721125