54 Alexandra

54 Alexandra
	A three-dimensional model of 54 Alexandra based on its light curve (top) and images of the asteroid (bottom)
Discovery
Discovered by	H. Goldschmidt
Discovery date	10 September 1858
Designations
Pronunciation	/ˌælɪɡˈzændrə, -ˈzɑːn-/ AL-ig-ZA(H)N-drə
Named after	Alexander von Humboldt; (German explorer)
Minor planet category	Main belt
Adjectives	Alexandrian
Orbital characteristics
	Epoch 31 December 2006 (JD 2454100.5)
Aphelion	485.483 million km (3.245 AU)
Perihelion	326.043 million km (2.179 AU)
Semi-major axis	405.763 million km (2.712 AU)
Eccentricity	0.196
Orbital period (sidereal)	1,631.620 d (4.47 a)
Mean anomaly	103.809°
Inclination	11.804°
Longitude of ascending node	313.446°
Argument of perihelion	345.594°
Physical characteristics
Dimensions	160 × 135 km (± 1 km)
Mean diameter	143 ± 5 km
Mass	(2.83±0.31)×1018 kg
Mean density	1.85±0.29 g/cm3
Synodic rotation period	7.022642 h; 18.14 h
Pole ecliptic longitude	155°±4°
Pole ecliptic latitude	17°±3°
Geometric albedo	0.056
Spectral type	Tholen = C; SMASS = C
Absolute magnitude (H)	7.66

54 Alexandra is a carbonaceous asteroid from the intermediate asteroid belt, approximately 155 kilometers in diameter. It was discovered by German-French astronomer Hermann Goldschmidt on 10 September 1858, and named after the German explorer Alexander von Humboldt; it was the first asteroid to be named after a male.

Description

On 17 May 2005, this asteroid occulted a faint star (magnitude 8.5) and the event was observed and timed in a number of locations within the U.S. and Mexico. As a result, a silhouette profile was produced, yielding a roughly oval cross-section with dimensions of 160 × 135 km (± 1 km). The mass of the asteroid can be estimated based upon the mutually perturbing effects of other bodies, yielding a composite estimate of (6.16±3.50)×10¹⁸ kg.

Photometric observations of this asteroid during 1990–92 gave a light curve with a period of 18.14 ± 0.04 hours and a brightness variation of 0.10 in magnitude. Alexandra has been studied by radar. It was the namesake and largest member of the former Alexandra asteroid family; a dynamic group of C-type asteroids that share similar orbital elements. Other members included 70 Panopaea and 145 Adeona. 145 Adeona was subsequently assigned to the Adeona family, with Alexandra and Panopaea being dropped.

In popular culture

In the Swedish film Aniara, 54 Alexandra is the closest celestial body which the off-course and out-of-control spacecraft will approach before it leaves the Solar System.^{[citation needed]}

Notes

↑ Calculated from its standard gravitational parameter GM = 0.189±0.021 km³/s².

References

1 2 3 4 5 Yeomans, Donald K. "54 Alexandra". JPL Small-Body Database Browser. NASA Jet Propulsion Laboratory. Retrieved 7 April 2013.
↑ "Alexandra". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 22 March 2020.
"Alexandra". Dictionary.com Unabridged (Online). n.d.
1 2 D.W. Dunham, "Upcoming Asteroid Occultations", Sky & Telescope, June, 2006, p. 63.
1 2 3 4 Hanuš, J.; et al. (May 2017), "Volumes and bulk densities of forty asteroids from ADAM shape modeling", Astronomy & Astrophysics, 601: 41, arXiv:1702.01996, Bibcode:2017A&A...601A.114H, doi:10.1051/0004-6361/201629956, A114.
1 2 Fuentes-Muñoz, Oscar; Farnocchia, Davide; Giorgini, Jon D.; Park, Ryan S. (1 December 2025). "Asteroid Mass Estimation by Mutual Perturbations During Close Encounters After Gaia Focused Product Release". The Astronomical Journal. 170 (6): 353. Bibcode:2025AJ....170..353F. doi:10.3847/1538-3881/ae0cc9. ISSN 0004-6256. S2CID 283347135.
1 2 Belskaya, I. N.; et al. (November 1993), "Physical Studies of Asteroids. Part XXVII. Photoelectric Photometry of Asteroids 14 Irene, 54 Alexandra and 56 Melete", Astronomy and Astrophysics Supplement, vol. 101, no. 3, pp. 507–511, Bibcode:1993A&AS..101..507B.
↑ "Asteroid Data Sets". Archived from the original on 17 December 2009. Retrieved 12 January 2007.
↑ Schmadel, Lutz D. (2003), Dictionary of Minor Planet Names (5th ed.), Springer, p. 20, ISBN 3642297188.
↑ Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, vol. 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
↑ "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 30 October 2011.
↑ Williams, J. G. (March 1988), "The Unusual Alexandra Family", Abstracts of the Lunar and Planetary Science Conference, vol. 19, pp. 1277–1278, Bibcode:1988LPI....19.1277W.
↑ Zappala, Vincenzo; et al. (December 1990), "Asteroid families. I - Identification by hierarchical clustering and reliability assessment", Astronomical Journal, vol. 100, pp. 2030–2046, 2045, Bibcode:1990AJ....100.2030Z, doi:10.1086/115658. See p. 2045 and family 44.

External links

Lightcurve plot of 54 Alexandra, Palmer Divide Observatory, B. D. Warner (2008)
Asteroid Lightcurve Database (LCDB), query form (info Archived 16 December 2017 at the Wayback Machine)
Dictionary of Minor Planet Names, Google books
Asteroids and comets rotation curves, CdR – Observatoire de Genève, Raoul Behrend
Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
54 Alexandra at AstDyS-2, Asteroids—Dynamic Site
- Ephemeris · Observation prediction · Orbital info · Proper elements · Observational info
54 Alexandra at the JPL Small-Body Database
- Close approach · Discovery · Ephemeris · Orbit viewer · Orbit parameters · Physical parameters

[6] Calculated from its standard gravitational parameter GM = 0.189±0.021 km³/s².

[jpldata-1] 1 2 3 4 5 Yeomans, Donald K. "54 Alexandra". JPL Small-Body Database Browser. NASA Jet Propulsion Laboratory. Retrieved 7 April 2013.

[2] "Alexandra". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 22 March 2020.
"Alexandra". Dictionary.com Unabridged (Online). n.d.

[Dunham-3] 1 2 D.W. Dunham, "Upcoming Asteroid Occultations", Sky & Telescope, June, 2006, p. 63.

[Hanus2017-4] 1 2 3 4 Hanuš, J.; et al. (May 2017), "Volumes and bulk densities of forty asteroids from ADAM shape modeling", Astronomy & Astrophysics, 601: 41, arXiv:1702.01996, Bibcode:2017A&A...601A.114H, doi:10.1051/0004-6361/201629956, A114.

[Fuentes-Muñoz2025-5] 1 2 Fuentes-Muñoz, Oscar; Farnocchia, Davide; Giorgini, Jon D.; Park, Ryan S. (1 December 2025). "Asteroid Mass Estimation by Mutual Perturbations During Close Encounters After Gaia Focused Product Release". The Astronomical Journal. 170 (6): 353. Bibcode:2025AJ....170..353F. doi:10.3847/1538-3881/ae0cc9. ISSN 0004-6256. S2CID 283347135.

[Belskaya1993-7] 1 2 Belskaya, I. N.; et al. (November 1993), "Physical Studies of Asteroids. Part XXVII. Photoelectric Photometry of Asteroids 14 Irene, 54 Alexandra and 56 Melete", Astronomy and Astrophysics Supplement, vol. 101, no. 3, pp. 507–511, Bibcode:1993A&AS..101..507B.

[8] "Asteroid Data Sets". Archived from the original on 17 December 2009. Retrieved 12 January 2007.

[Schmadel2003-9] Schmadel, Lutz D. (2003), Dictionary of Minor Planet Names (5th ed.), Springer, p. 20, ISBN 3642297188.

[Carry2012-10] Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, vol. 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.

[detected-11] "Radar-Detected Asteroids and Comets". NASA/JPL Asteroid Radar Research. Retrieved 30 October 2011.

[Williams1988-12] Williams, J. G. (March 1988), "The Unusual Alexandra Family", Abstracts of the Lunar and Planetary Science Conference, vol. 19, pp. 1277–1278, Bibcode:1988LPI....19.1277W.

[Zappala1990-13] Zappala, Vincenzo; et al. (December 1990), "Asteroid families. I - Identification by hierarchical clustering and reliability assessment", Astronomical Journal, vol. 100, pp. 2030–2046, 2045, Bibcode:1990AJ....100.2030Z, doi:10.1086/115658. See p. 2045 and family 44.