168 Sibylla

{{Short description|Outer main-belt asteroid}}

{{Use dmy dates|date=October 2019}}

{{Infobox planet

| minorplanet = yes

| background = #D6D6D6

|image= Орбита астероида 168.png

|caption=Orbital diagram

| name = 168 Sibylla

| discovery_ref = {{cite web | url=https://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html | title=Discovery Circumstances: Numbered Minor Planets (1)-(5000) | accessdate=August 14, 2012}}

| discoverer = J. C. Watson

| discovered = 28 September 1876

| discovery_site = Ann Arbor

| mpc_name = (168) Sibylla

| mp_category = main-belt

| alt_names = A876 SA; 1911 HF;
1949 MO

| pronounced={{IPAc-en|s|ᵻ|'|b|ɪ|l|ə}}{{OED|Sibylla}}

| adjective = Sibyllian {{IPAc-en|s|ᵻ|'|b|ɪ|l|i|ə|n}}

| orbit_ref = {{Cite web |url=http://ftp.lowell.edu/pub/elgb/astorb.html |website=astorb |title=The Asteroid Orbital Elements Database |publisher=Lowell Observatory |accessdate=August 14, 2012 }}

| epoch = 31 July 2016 (JD 2457600.5)

| aphelion = {{Convert|3.6215|AU|Gm|abbr=on|lk=on}}

| perihelion = {{Convert|3.1417|AU|Gm|abbr=on}}

| semimajor = {{Convert|3.3816|AU|Gm|abbr=on}}

| eccentricity = 0.070943

| period = 6.22 yr (2271.4 d)

| avg_speed = 16.19 km/s

| inclination = 4.6617°

| asc_node = 205.959°

| mean_anomaly = 171.517°

| arg_peri = 173.920°

| dimensions = {{val|148.39|4.0|ul=km}}
149.06 ± 4.29 km

| mass = {{nowrap|(3.92 ± 1.80) × 10¹⁸ kg}}

| density = 2.26 ± 1.05 g/cm³

| sidereal_day = 23.82 hours

| pole_ecliptic_lat =

| pole_ecliptic_lon =

| albedo = {{val|0.0535|0.003}}

| spectral_type = C

| abs_magnitude = 7.94

| mean_motion = {{Deg2DMS|0.15849|sup=ms}} / day

| observation_arc = 136.01 yr (49676 d)

| uncertainty = 0

| rotation = {{Convert|47.009|h|d|abbr=on|lk=on}}

|named_after=Sibyls

}}

168 Sibylla is a large main-belt asteroid, discovered by Canadian-American astronomer J. C. Watson on September 28, 1876. It was most likely named for the Sibyls, referring to the Ancient Greek female oracles. Based upon its spectrum this object is classified as a C-type asteroid, which indicates it is very dark and composed of primitive carbonaceous materials. 168 Sibylla is a Cybele asteroid, orbiting beyond most of the main-belt asteroids.

Photometric observations of this asteroid made at the Torino Observatory in Italy during 1990–1991 were used to determine a synodic rotation period of 23.82 ± 0.004 hours. The shape of this slowly rotating object appears to resemble an oblate spheroid.