 Orbital diagram | |
| Discovery | |
|---|---|
| Discovered by | Karl Theodor Robert Luther |
| Discovery date | March 15, 1863 |
| Designations | |
| (78) Diana | |
| Pronunciation | /daɪˈænə,daɪˈeɪnə/dy-A(Y)N-ə[1] |
Named after | Diāna(Roman mythology) |
| Main belt | |
| Adjectives | Dianian (/daɪˈeɪniən/dy-AY-nee-ən) |
| Orbital characteristics[2] | |
| Epoch December 31, 2006 (JD 2454100.5) | |
| Aphelion | 473.182 Gm (3.163 AU) |
| Perihelion | 310.686 Gm (2.077 AU) |
| 391.934 Gm (2.620 AU) | |
| Eccentricity | 0.207 |
| 1,548.922 d (4.24 yr) | |
Averageorbital speed | 18.20 km/s |
| 353.808° | |
| Inclination | 8.688° |
| 333.582° | |
| 151.423° | |
| Physical characteristics | |
| Dimensions | 123.63±4.57 km[3] |
| Mass | (1.27±0.13)×1018 kg[3] |
Meandensity | 1.28±0.19[3] g/cm3 |
| 7.2991[4] h | |
| 0.071[5] | |
| C | |
| 8.09 | |
78 Diana is a large and darkmain-beltasteroid. It was discovered by German astronomerRobert Luther on March 15, 1863,[6] and named afterDiana,Roman goddess of the hunt. The asteroid is orbiting theSun at a distance of 2.620 AU with a period of 4.24 years and aneccentricity (ovalness) of 0.207. Theorbital plane is tilted at an angle of 8.688° relative to theplane of the ecliptic.[2] Its composition iscarbonaceous and primitive.
Photometric observations of this asteroid during 1986 and 2006–08 gave alight curve with a rotation period of 7.2991 hours and a brightness variation in the range 0.02–0.104magnitude.[4] Based upon radar data, the near surface solid density of the asteroid is 2.7+0.8
−0.5 g cm−3.[7] 78 Dianaocculted astar on September 4, 1980. A diameter of 116 km was measured, closely matching the value given by theIRASsatellite.
Diana is expected to pass about 0.003 AU (450,000 km; 280,000 mi) from(29075) 1950 DA on August 5, 2150.[8] Main-belt asteroid4217 Engelhardt (~9 km in diameter) will pass about 0.0017 AU (250,000 km; 160,000 mi) from (29075) 1950 DA in 2736.[8]
