1421 Esperanto, provisional designation 1936 FQ, is a dark background asteroid from the outer regions of the asteroid belt, approximately 55 kilometers (34 miles) in diameter. It was discovered on 18 March 1936, by Finnish astronomer Yrjö Väisälä at the Iso-Heikkilä Observatory in Turku, southwest Finland. The presumed C-type asteroid has a rotation period of nearly 22 hours.[12] It was named for the artificial language Esperanto.[1]

1421 Esperanto
Discovery [1]
Discovered byY. Väisälä
Discovery siteTurku Obs.
Discovery date18 March 1936
MPC designation(1421) Esperanto
Named after
(artificial language)
1936 FQ · 1931 HC
1958 GD · A906 UD
A917 XD · A920 GD
main-belt[1][2] · (outer)
Orbital characteristics[2]
Epoch 27 April 2019 (JD 2458600.5)
Uncertainty parameter 0
Observation arc111.92 yr (40,879 d)
Aphelion3.3505 AU
Perihelion2.8280 AU
3.0893 AU
5.43 yr (1,983 d)
0° 10m 53.4s / day
Physical characteristics
Mean diameter
43.31±3.1 km[5]
51.95±10.21 km[6][7]
56.68±0.96 km[8]
62.06±17.35 km[9]
64.37±25.60 km[10]
21.982±0.005 h[11]
C (assumed)[12]

Orbit and classificationEdit

Esperanto has been determined a non-family asteroid from the main belt's background population by means of modern HCM-analysis, after it had previously been grouped to the Eos family by Zappalà in the 1990s.[3][4]

It orbits the Sun in the outer asteroid belt at a distance of 2.8–3.4 AU once every 5 years and 5 months (1,983 days; semi-major axis of 3.09 AU). Its orbit has an eccentricity of 0.08 and an inclination of 10° with respect to the ecliptic.[2] The body's observation arc begins with its first observation as 1906 UD at Heidelberg Observatory in October 1906, almost 30 years prior to its official discovery observation at Turku.[1]


This minor planet was named by the discoverer after the artificial language, Esperanto, which was created by inventor and writer, Ludwik Lejzer Zamenhof (1859–1917), who used the pseudonym "Doktoro Esperanto".[1] The discoverer also named another asteroid, 1462 Zamenhof, directly after the inventor. Both asteroids are considered to be the most remote Zamenhof-Esperanto objects. The official naming citation was published by the Minor Planet Center in January 1956 (M.P.C. 1350).[13]

Physical characteristicsEdit

Esperanto is an assumed, carbonaceous C-type asteroid.[12]

Rotation periodEdit

In March 2012, a rotational lightcurve of Esperanto was obtained from photometric observations by Andrea Ferrero at the Bigmuskie Observatory (B88) in northern Italy. Lightcurve analysis gave a rotation period of 21.982±0.005 hours with a brightness amplitude of 0.15 magnitude (U=3-).[11]

Diameter and albedoEdit

According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Esperanto measures between 43.3 and 64.3 kilometers in diameter and its surface has an albedo between 0.03 and 0.098.[5][6][7][8][9][10]

The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0714 and a diameter of 43.31 kilometers based on an absolute magnitude of 10.3.[12][5]


  1. ^ a b c d e f g "1421 Esperanto (1936 FQ)". Minor Planet Center. Retrieved 9 December 2018.
  2. ^ a b c d "JPL Small-Body Database Browser: 1421 Esperanto (1936 FQ)" (2018-09-18 last obs.). Jet Propulsion Laboratory. Retrieved 9 December 2018.
  3. ^ a b "Asteroid 1421 Esperanto". Small Bodies Data Ferret. Retrieved 9 December 2018.
  4. ^ a b "Asteroid (1421) Esperanto – Proper elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 4 December 2018.
  5. ^ a b c d Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System – IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 9 December 2018.
  6. ^ a b c d Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; et al. (June 2016). "NEOWISE Diameters and Albedos V1.0". NASA Planetary Data System. Bibcode:2016PDSS..247.....M. Retrieved 9 December 2018.
  7. ^ 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" (PDF). The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 9 December 2018.
  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. Retrieved 9 December 2018. (online, AcuA catalog p. 153)
  9. ^ 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" (PDF). The Astrophysical Journal. 814 (2): 13. arXiv:1509.02522. Bibcode:2015ApJ...814..117N. doi:10.1088/0004-637X/814/2/117. Retrieved 9 December 2018.
  10. ^ 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" (PDF). The Astronomical Journal. 152 (3): 12. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. Retrieved 9 December 2018.
  11. ^ a b Ferrero, Andrea (July 2012). "Lightcurve Photometry of Six Asteroids". The Minor Planet Bulletin. 39 (3): 138–139. Bibcode:2012MPBu...39..138F. ISSN 1052-8091. Retrieved 9 December 2018.
  12. ^ a b c d "LCDB Data for (1421) Esperanto". Asteroid Lightcurve Database (LCDB). Retrieved 9 December 2018.
  13. ^ 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