1731 Smuts, provisional designation 1948 PH, is a carbonaceous asteroid from the outer region of the asteroid belt, approximately 54 kilometers in diameter. It was discovered on 9 August 1948, by South African astronomer Ernest Johnson at Johannesburg Observatory in South Africa, who named it after Field marshal Jan Smuts.[2][8]

1731 Smuts
Discovered byE. Johnson
Discovery siteJohannesburg Obs.
Discovery date9 August 1948
(1731) Smuts
Named after
Jan Smuts
(Field Marshal; PM)[2]
1948 PH · 1926 TF
1931 QA · 1935 FS
1938 YB · 1941 KG
1947 LC · 1948 PP
1954 SX · 1960 WE
1966 UY
main-belt · (outer)[3]
Orbital characteristics[1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc90.22 yr (32,954 days)
Aphelion3.5712 AU
Perihelion2.7652 AU
3.1682 AU
5.64 yr (2,060 days)
0° 10m 29.28s / day
Physical characteristics
Dimensions53.83 km (derived)[3]
54.71±0.98 km[4]
57.491±0.432 km[6]
12.5±0.7 h[7]
0.0385 (derived)[3]
10.00[4][6] · 10.5[1][3]

Classification and orbitEdit

Smuts orbits the Sun in the outer main-belt at a distance of 2.8–3.6 AU once every 5 years and 8 months (2,060 days). Its orbit has an eccentricity of 0.13 and an inclination of 6° with respect to the ecliptic.[1] First identified as 1926 TF in Heidelberg, Smuts's first used observation was taken one month later in November 1926, extending the body's observation arc by 22 years prior to its official discovery observation.[8]

Physical characteristicsEdit

Smuts has been characterized as a carbonaceous C-type asteroid.[3]

Rotation periodEdit

In March 2008, a rotational lightcurve of Smuts was obtained from photometric observations by French amateur astronomer René Roy. It gave a rotation period of 12.5 hours with a brightness variation of 0.8 magnitude (U=2).[7]

Diameter and albedoEdit

According to the surveys carried out by the Japanese Akari satellite and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Smuts measures between 54.71 and 57.49 kilometers in diameter, and its surface has an albedo between 0.053 and 0.059.[4][5][6] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0385 and a diameter of 53.83 kilometers based on an absolute magnitude of 10.5.[3]


This minor planet was named after prominent South African and British Commonwealth statesman, Field Marshal and philosopher, Jan Smuts (1870–1950), under whom the discoverer of the asteroid fought in both World Wars.[2]

Smuts captured German South-West Africa in World War I and 0.0385 the only man to sign both of the peace treaties ending the First and Second World Wars. He served as prime minister of South Africa from 1919 until 1924 and again from 1939 until 1948.[2] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3933).[9]


  1. ^ a b c d "JPL Small-Body Database Browser: 1731 Smuts (1948 PH)" (2016-12-25 last obs.). Jet Propulsion Laboratory. Retrieved 7 June 2017.
  2. ^ a b c d Schmadel, Lutz D. (2007). "(1731) Smuts". Dictionary of Minor Planet Names – (1731) Smuts. Springer Berlin Heidelberg. p. 137. doi:10.1007/978-3-540-29925-7_1732. ISBN 978-3-540-00238-3.
  3. ^ a b c d e f g "LCDB Data for (1731) Smuts". Asteroid Lightcurve Database (LCDB). Retrieved 21 December 2016.
  4. ^ 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)
  5. ^ a b c 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.
  6. ^ a b c d 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.
  7. ^ a b Behrend, Raoul. "Asteroids and comets rotation curves – (1731) Smuts". Geneva Observatory. Retrieved 21 December 2016.
  8. ^ a b "1731 Smuts (1948 PH)". Minor Planet Center. Retrieved 21 December 2016.
  9. ^ Schmadel, Lutz D. "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.

External linksEdit