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]
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] | |
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.