Rhodope (minor planet designation: 166 Rhodope) is a dark background asteroid from the central region of the asteroid belt, approximately 55 kilometers in diameter. It was discovered on 15 August 1876, by German–American astronomer Christian Peters at the Litchfield Observatory in Clinton, New York, United States.[17] The asteroid was named after Queen Rhodope from Greek mythology.[2]

166 Rhodope
166Rhodope (Lightcurve Inversion).png
Lightcurve-based 3-D model of Rhodope
Discovered byC. H. F. Peters
Discovery siteLitchfield Obs.
Discovery date15 August 1876
(166) Rhodope
Named after
Queen Rhodope[2]
(Greek mythology)
A876 PB
main-belt · (middle)
background[3] · Eunomia[4]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc132.05 yr (48,233 days)
Aphelion3.2539 AU
Perihelion2.1165 AU
2.6852 AU
4.40 yr (1,607 days)
0° 13m 26.4s / day
Physical characteristics
Dimensions39.04±9.79 km[6]
52.393±0.196 km[7]
53.26±0.62 km[8]
54.551±1.535 km[9]
54.56 km (taken)[4]
54.564 km[10]
62.34±21.46 km[11]
65.29±0.80 km[12]
4.714793 h[13]
4.712 h[a]
4.715 h[4]
4.7152±0.0002 h[14]
7.87±0.03 h(poor)[15]
Tholen = GC:[1]
SMASS = Xe[1]
C[16] · P[9] · X[4]
B–V = 0.725[1]
U–B = 0.425[1]
9.75[4] · 9.75±0.05[10][15] · 9.89[1][6][8][9][12] · 9.95[11] · 10.22±0.25[16]

Orbit and classificationEdit

Rhodope is a non-family asteroid of the main belt's background population, when applying the Hierarchical Clustering Method to its proper orbital elements.[3] Alternatively, it has been dynamically assigned to the stony Eunomia family (502),[4] which have a different spectral class and albedo than that of Rhodope though.[18]: 23  The asteroid has also been considered a member of the Adeona family.[citation needed]

Rhodope orbits the Sun in the central asteroid belt at a distance of 2.1–3.3 AU once every 4 years and 5 months (1,607 days). Its orbit has an eccentricity of 0.21 and an inclination of 12° with respect to the ecliptic.[1] The body's observation arc begins with the first recorded observation by the MPC at Vienna Observatory on 10 September 1885, or more than 9 years after its official discovery observation at Clinton.[17]

On 19 October 2005, it was observed occulting the prominent star Regulus from Vibo Valentia, Italy.[19]

Physical characteristicsEdit

Spectral typeEdit

Rhodope's spectral type is ambiguous. In the Tholen classification, the noisy spectrum is closest to a G-type and somewhat similar to a common C-type (GC:).[1] In the SMASS classification, it is an Xe-subtype, that transitions from the X-type to the very bright E-type.[1] In addition, Rhodope has also been characterized as a primitive P-type and carbonaceous C-type by the Wide-field Infrared Survey Explorer (WISE) and by Pan-STARRS photometric survey, respectively.[9][16]

Rotation periodEdit

Two well-defined rotational lightcurves of Rhodope were obtained from photometric observations by French astronomer Matthieu Conjat and by an anonymous observer of the Collaborative Asteroid Lightcurve Link (CALL). Lightcurve analysis gave a consolidated rotation period of 4.715 hours with a brightness variation of 0.35 to 0.36 magnitude (U=3/3).[4][14][a] The result supersedes a period of 7.87 hours measured by Alan Harris in the early 1980s (U=1).[15]


In 2013, the asteroid's lightcurve was also modeled from combined dense and sparse photometry. It gave a concurring sidereal period of 4.714793 hours. The modelling also determined two spin axis of (345.0°, −22.0°) and (173.0°, −3.0°) in ecliptic coordinates (λ, β).[13]

Diameter and albedoEdit

According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's WISE telescope, Rhodope measures between 39.04 and 65.29 kilometers in diameter and its surface has an albedo between 0.046 and 0.10.[6][7][8][9][10][11][12]

CALL adopts Petr Pravec's revised WISE-data, that is, an albedo of 0.0747 and a diameter of 54.56 kilometers based on an absolute magnitude of 9.75.[4][10]


This minor planet was named from Greek mythology after Queen Rhodope of Thrace, wife of King Haemus and attendant of Artemis, also see (105). In vanity, Rhodope and Haemus compared themselves to the gods Zeus and Hera, see (5731) and (103), who punished the couple by changing them into the Rhodope Mountains and Balkan Mountains, respectively.[2]


  1. ^ a b Anonymous lightcurve –CALL-2011 (web) web: rotation period 4.712 hours with a brightness amplitude of 0.35 mag. Quality code of 3. Summary figures for (166) Rhodope at LCDB


  1. ^ a b c d e f g h i j "JPL Small-Body Database Browser: 166 Rhodope" (2017-10-01 last obs.). Jet Propulsion Laboratory. Retrieved 28 October 2017.
  2. ^ a b c Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (166) Rhodope. Springer Berlin Heidelberg. p. 30. doi:10.1007/978-3-540-29925-7_167. ISBN 978-3-540-00238-3.
  3. ^ a b "Asteroid 166 Rhodope". Small Bodies Data Ferret. Retrieved 24 October 2019.
  4. ^ a b c d e f g h "LCDB Data for (166) Rhodope". Asteroid Lightcurve Database (LCDB). Retrieved 28 October 2017.
  5. ^ Noah Webster (1884) A Practical Dictionary of the English Language
  6. ^ a b c d Nugent, C. R.; Mainzer, A.; Masiero, J.; Bauer, J.; Cutri, R. M.; Grav, T.; et al. (December 2015). "NEOWISE Reactivation Mission Year One: Preliminary Asteroid Diameters and Albedos". The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117.
  7. ^ a b Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121.
  8. ^ a b c d Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. (online, AcuA catalog p. 153)
  9. ^ a b c d e f Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
  10. ^ a b c d e Pravec, Petr; Harris, Alan W.; Kusnirák, Peter; Galád, Adrián; Hornoch, Kamil (September 2012). "Absolute magnitudes of asteroids and a revision of asteroid albedo estimates from WISE thermal observations". Icarus. 221 (1): 365–387. Bibcode:2012Icar..221..365P. doi:10.1016/j.icarus.2012.07.026.
  11. ^ a b c d Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63.
  12. ^ a b c d Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8.
  13. ^ a b Hanus, J.; Durech, J.; Broz, M.; Marciniak, A.; Warner, B. D.; Pilcher, F.; et al. (March 2013). "Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution". Astronomy and Astrophysics. 551: 16. arXiv:1301.6943. Bibcode:2013A&A...551A..67H. doi:10.1051/0004-6361/201220701.
  14. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (166) Rhodope". Geneva Observatory. Retrieved 28 October 2017.
  15. ^ a b c Harris, A. W.; Young, J. W.; Bowell, E.; Tholen, D. J. (November 1999). "Asteroid Lightcurve Observations from 1981 to 1983". Icarus. 142 (1): 173–201. Bibcode:1999Icar..142..173H. doi:10.1006/icar.1999.6181.
  16. ^ a b c Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007.
  17. ^ a b "166 Rhodope". Minor Planet Center. Retrieved 28 October 2017.
  18. ^ Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
  19. ^ Sigismondi, Costantino; Troise, Davide (September 2008). "Asteroidal Occultation of Regulus:. Differential Effect of Light Bending". "THE ELEVENTH MARCEL GROSSMANN MEETING on Recent Developments in Theoretical and Experimental General Relativity: 2594–2596". Bibcode:2008mgm..conf.2594S. doi:10.1142/9789812834300_0469. ISBN 978-981-283-426-3.

External linksEdit