Discovery [1] | |
---|---|
Discovered by | H. Goldschmidt |
Discovery date | 10 September 1858 |
Designations | |
(54) Alexandra | |
Pronunciation | /ˌælɪɡˈzændrə,-ˈzɑːn-/ AL-ig-ZA(H)N-drə [2] |
Named after | Alexander von Humboldt (German explorer) |
Main belt | |
Adjectives | Alexandrian |
Orbital characteristics | |
Epoch December 31, 2006 (JD 2454100.5) | |
Aphelion | 485.483 Gm (3.245 AU) |
Perihelion | 326.043 Gm (2.179 AU) |
405.763 Gm (2.712 AU) | |
Eccentricity | 0.196 |
1,631.620 d (4.47 a) | |
103.809° | |
Inclination | 11.804° |
313.446° | |
345.594° | |
Physical characteristics | |
Dimensions | 160 × 135 km (± 1 km) |
Mean diameter | 154.137 km [1] |
Mass | (6.16±3.50)×1018 kg [3] |
Mean density | 3.50±2.11 g/cm3 [3] |
18.14 h [4] | |
Pole ecliptic latitude | 155°±4° [5] |
Pole ecliptic longitude | 17°±3° [5] |
0.056 [1] [6] | |
Tholen = C [1] SMASS = C [1] | |
7.66 [1] | |
Alexandra (minor planet designation: 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. [7]
On May 17, 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). [8] The mass of the asteroid can be estimated based upon the mutually perturbing effects of other bodies, yielding an estimate of (6.16±3.50)×1018 kg. [3]
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. [4] Alexandra has been studied by radar. [9] 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. [10] 145 Adeona was subsequently assigned to the Adeona family, with Alexandra and Panopaea being dropped. [11]
In the Swedish film Aniara (2018) it is mentioned that 54 Alexandra is the closest celestial body which the off-course and out-of-control spacecraft will approach before it leaves the Solar System.
Nemausa is a large main-belt asteroid that was discovered on January 22, 1858, by Joseph Jean Pierre Laurent. Laurent made the discovery from the private observatory of Benjamin Valz in Nîmes, France. The house, at 32 rue Nationale in Nîmes, has a plaque commemorating the discovery. With Laurent's permission, Valz named the asteroid after the Celtic god Nemausus, the patron god and namesake of Nîmes during Roman times.
Parthenope is a large, bright main-belt asteroid.
Egeria is a large main-belt G-type asteroid. It was discovered by Annibale de Gasparis on November 2, 1850. Egeria was named by Urbain Le Verrier, whose computations led to the discovery of Neptune, after the mythological nymph Egeria of Aricia, Italy, the wife of Numa Pompilius, second king of Rome.
Melpomene is a large, bright main-belt asteroid that was discovered by J. R. Hind on 24 June 1852, and named after Melpomenē, the Muse of tragedy in Greek mythology. Its historical symbol was a dagger over a star; it is in the pipeline for Unicode 17.0 as U+1CECB .
Atalante is a large, dark main-belt asteroid. It was discovered by the German-French astronomer H. Goldschmidt on October 5, 1855, and named by French mathematician Urbain Le Verrier after the Greek mythological heroine Atalanta. It was rendered 'Atalanta' in English sources in the 19th century. This asteroid is classified as C-type (carbonaceous), according to the Tholen classification system.
Daphne is a large asteroid from the asteroid belt. It is a dark-surfaced body 174 km in diameter is probably composed of primitive carbonaceous chondrites. The spectra of the asteroid displays evidence of aqueous alteration. It was discovered by H. Goldschmidt on May 22, 1856, and named after Daphne, the nymph in Greek mythology who was turned into a laurel tree. Incorrect orbital calculations initially resulted in 56 Melete being mistaken for a second sighting of Daphne. Daphne was not sighted again until August 31, 1862.
Pales is a large, dark main-belt asteroid. It was discovered by German-French astronomer Hermann Goldschmidt on 19 September 1857 from his balcony in Paris. The asteroid is named after Pales, the goddess of shepherds in Roman mythology. Since it was discovered on the same night as 48 Doris, geologist Élie de Beaumont suggested naming the two "The Twins".
Melete is a large and dark main belt asteroid. It is a rather unusual P-type asteroid, probably composed of organic rich silicates, carbon and anhydrous silicates, with possible internal water ice. The asteroid orbits the Sun with a period of 4.18 years.
Panopaea is a large main belt asteroid. Its orbit is close to those of the Eunomia asteroid family; however, Panopaea is a dark, primitive carbonaceous C-type asteroid in contrast to the S-type asteroids of the Eunomian asteroids. The spectra of the asteroid displays evidence of aqueous alteration. Photometric studies give a rotation period of 15.797 hours and an amplitude of 0.11±0.01 in magnitude. Previous studies that suggested the rotation period may be twice this amount were rejected based upon further observation.
Frigga is a large, M-type, possibly metallic main-belt asteroid. It was discovered by the German-American astronomer C. H. F. Peters on November 12, 1862. The object is named after Frigg, the Norse goddess. The asteroid is orbiting the Sun with a period of 4.36 years and completes a rotation on its axis every nine hours.
Miriam is a moderately large, very dark main belt asteroid. It was discovered by C. H. F. Peters on August 22, 1868, from the Litchfield Observatory.
Artemis is a main-belt asteroid that was discovered by J. C. Watson on September 16, 1868, at Ann Arbor, Michigan. It was named after Artemis, the goddess of the hunt, Moon, and crossways in Greek Mythology.
137 Meliboea is a large, dark main-belt asteroid that was discovered by Austrian astronomer J. Palisa at the Austrian Naval Observatory on 21 April 1874, the second of his many asteroid discoveries. It was later named after Meliboea, the daughter of Oceanus and Tethys in Greek mythology. The largest body in the Meliboea family of asteroids that share similar orbital elements, only 791 Ani approaches its size. It is classified as a C-type asteroid and may be composed of carbonaceous materials. The spectra of the asteroid displays evidence of aqueous alteration.
Lucina is a main-belt asteroid that was discovered by Alphonse Borrelly on June 8, 1875, and named after Lucina, the Roman goddess of childbirth. It is large, dark and has a carbonaceous composition. The spectra of the asteroid displays evidence of aqueous alteration.
Adeona is a large asteroid from the intermediate asteroid belt, approximately 150 kilometers in diameter. Its surface is very dark, and, based upon its classification as a C-type asteroid, is probably composed of primitive carbonaceous material. The spectra of the asteroid displays evidence of aqueous alteration. The Adeona family of asteroids is named after it.
161 Athor is an M-type Main belt asteroid that was discovered by James Craig Watson on April 19, 1876, at the Detroit Observatory and named after Hathor, an Egyptian fertility goddess. It is the namesake of a proposed Athor asteroid family, estimated to be ~3 billion years old.
Isolda is a very large, dark main-belt asteroid. It is classified as a C-type asteroid and is probably composed of primitive carbonaceous material. The spectra of the asteroid displays evidence of aqueous alteration.
Sapientia is a very large Main belt asteroid that was discovered by Johann Palisa on 15 April 1888 in Vienna. It is classified as a C-type asteroid and is probably composed of carbonaceous material. It is named for the Roman personification of wisdom, Sapientia.
402 Chloë is a large main-belt asteroid. It was discovered by French astronomer Auguste Charlois on 21 March 1895 from Nice. This asteroid is orbiting the Sun at a distance of 2.56 AU with a period of 4.09 years and an eccentricity of 0.11. The orbital plane is inclined at an angle of 11.8° to the plane of the ecliptic.
790 Pretoria is a minor planet orbiting the Sun that was discovered by English astronomer Harry Edwin Wood on January 16, 1912. It is a member of the Cybele group located beyond the core of the main belt and named after Pretoria, the capital city of South Africa.