{{Infoboks planet
| navn=15 Eunomia
| oppdaget av=A. de Gasparis
| oppdaget fra=Napoli
| oppdaget dato=29. juli 1851
| kategori= hovedbeltet(Eunomia)
| epoke=2454600,5 JD (14. mai 2008)
| store halvakse=395,515 mill. km (2,644 AE)
| perihel=321,363 mill. km (2,148 AE)
| aphel=469,667 mill. km (3,140 AE)
| eksentrisitet=0,187
| omløpstid=1570,201 d (4,30 år)
| inklinasjon=11,739
| oppstigende knute=293,268
| perihelargument=97,869
| gjennomsnittlig anomali=86,643
| dimensjoner=255,33 km
| rotasjon=6,083 t
| spektralklasse=S <small>(Tholen)</small><br>S <small>(SMASS)</small>
| absolutt størrelsesklasse=5,28
|overflaterefleksjon=0,209}}

'''15 Eunomia''' er en hovedbelteEunomia.<ref>[http://www.psi.edu/pds/resource/family.html «Zappala, V., Ph. Bendjoya, A. Cellino, P. Farinella, and C. Froeschle, Asteroid Dynamical Families. EAR-A-5-DDR-FAMILY-V4.1. NASA Planetary Data System, 1997»]</ref> Den ble oppdaga den 29. juli 1851 av Annibale de Gasparis fra Osservatorio Astronomico di Capodimonte.

== Kilder ==

<references/>
* ''[http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=15 15 Eunomia - baneparametre hos] [http://ssd.jpl.nasa.gov/ JPL Solar System Dynamics]''
* ''Oppdagere og oppdagingsplasser i [http://en.wikipedia.org/wiki/List_of_asteroids_%281-1000%29 Engelsk Wikipedia sine asteroidelister]. Listene baserer seg på [http://www.cfa.harvard.edu/iau/lists/NumberedMPs.html Minor Planet Center - «Discovery Circumstances: Numbered Minor Planets»]''

<!-- Additional parameters for this template  are available at Template:Infobox Planet. -->
{{Infobox Planet | discovery=yes | physical_characteristics = yes | bgcolour=#FFFFC0 |
 name=15 Eunomia
 | image=
 | symbol= 15px
 | discoverer=Annibale de Gasparis
 | discovered=July 29, 1851
 | alt_names=''none''
 | mp_category=Main belt, (Eunomia family)
 | epoch=JD 2453900.5)
 | semimajor=395.429 Gm (2.643 AU)
 | perihelion=321.429 Gm (2.149 AU)
 | aphelion=469.429 Gm (3.138 AU)
 | eccentricity=0.187
 | period=1569.687 d (4.30 a)
 | inclination=11.738°
 | asc_node=293.273°
 | arg_peri=97.909°
 | mean_anomaly=286.102°
 | avg_speed=18.16 km/s
 | dimensions=330×245×205<ref name="IRAS">[http://www.psi.edu/pds/asteroid/IRAS_A_FPA_3_RDR_IMPS_V6_0/data/diamalb.tab Supplemental IRAS Minor Planet Survey]</ref><ref name="Nathues05">Nathues, A.; et al.; (2005); [http://www.rni.helsinki.fi/~mjk/Eunomia.pdf ''Spectral study of the Eunomia asteroid family - I. Eunomia''], Icarus, Vol. 175, p. 452</ref><ref name="Tanga03">Tanga, P.; et al.; (2003); [http://www.edpsciences.org/articles/aa/pdf/2003/14/aa3023.pdf?access=ok ''Asteroid observations with the Hubble Space Telescope'']; Astronomy & Astrophysics, Vol. 401, p. 733</ref>
 | mass=3.26±0.12 kg<ref name="VitaglianoStoss06">Stoss, R. M.; Vitagliano, A.; (2006); [http://www.edpsciences.org/articles/aa/pdf/forthpdf/aa5760-06_forth.pdf ''New mass determination of (15) Eunomia based on a very close encounter with '']; Astronomy & Astrophysics manuscript no. aa5760-06</ref>
 | density=3.8±0.7 g/cm³
 | surface_grav=0.08 m/s²
 | escape_velocity=0.16 km/s
 | rotation=0.2535 d (6.083 h)<ref>[http://www.psi.edu/pds/archive/lc.html Planetary Data System (PDS) lightcurve data]</ref>
 | spectral_type=S-type asteroid
 | magnitude = 7.9<ref name="Pasachoff1983"></ref> to 11.24
 | abs_magnitude=5.28
 | albedo=0.209&nbsp;(geometric)<ref name="IRAS"/>
 | angular_size = 0.29" <!-- Horizons 2028-Oct-22 --> to 0.085"
 | single_temperature=~166 K<br/>''max:'' 260 K (-13 °C)}}
'''15 Eunomia''' (, )'' is a very large main asteroid belt. It is the largest of the stony (S-type) asteroids, and somewhere between the 8th to 12th largest Main Belt asteroid overall (uncertainty in diameters causes uncertainty in its ranking). It is also the largest member of the Eunomia family of asteroids. 

Eunomia was discovered by Eunomia, one of the Horae (Hours), a personification of order and law in Greek mythology.

==Characteristics==
As the largest S-type asteroid (with 3 Juno being a very close second), Eunomia has attracted a moderate amount of scientific attention. It contains slightly over one percent of the mass of the entire main belt. 

Eunomia appears to be an elongated but fairly regularly shaped body, with what appear to be four sides of differing curvature and noticeably different average compositions.<ref name="Nathues05"/> Its elongation led to the suggestion that Eunomia may be a binary object. However, this has been refuted.<ref name="Tanga03"/> It is a retrograde rotator with its pole pointing towards ecliptic coordinates (β, λ) = (-65°, 2°) with a 10°  uncertainty.<ref name="Nathues05"/><ref name="Tanga03"/> This gives an axial tilt of about 165°.

Like other true members of the family, its surface is composed of Spectroscopic studies suggest that Eunomia has regions with differing composition. A larger region dominated by olivine, which is pyroxene poor and metal rich, and another somewhat smaller region on one hemisphere (the less pointed end) that is noticeably richer in pyroxene,<ref name="Nathues05"/> and has a generally Reed, K. L.; Gaffey, M. J.; and Lebofsky, L. A.; (1997); ''Shape and Albedo Variations of Asteroid 15 Eunomia'', Icarus, Vol. 125, p. 446</ref>

This composition indicates that the parent body was likely subject to M-type) bodies. 

Altogether these lines of evidence suggest that Eunomia is the central remnant of the parent body of the Michel, P.; Benz, W.; and Richardson, D. C.; (2001); ''Catastrophic disruption of pre-shattered parent bodies'', Icarus, Vol. 168, p. 420</ref> are more consistent with Eunomia being a re-accumulation of most of the fragments of a completely shattered parent body. Coversely again, Eunomia's quite high density would indicate that it is not a rubble pile after all. Whetever the case in this respect, it appears that any metallic core region, if present, has not been exposed.

An older explanation of the compositional differences, that Eunomia is a mantle fragment of a far larger parent body (with a bit of crust on one end, and a bit of core on the other) appears to be ruled out by studies of the mass distribution of the entire Eunomia family of asteroids. These indicate that the largest remaining fragment  (that is, Eunomia) should have about 70% of the mass of the parent body,<ref name="Tanga99">Tanga, P.; et al.; (1999); ''On the Size Distribution of Asteroid Families: The Role of Geometry'', Icarus, Vol. 141, p. 65</ref> which is consistent with Eunomia being a ''central'' remnant, with the crust and a part of the mantle stripped off.

These indications are also in accord with fresh mass determinations which indicate that Eunomia has a typical density for mostly intact stony asteroids, and not the anomalously low "rubble pile" density of ~1 g/cm³ that had been obtained earlier.