| Minorplanet: | yes |
| Background: |
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| 78 Diana | |
| Discovered: | March 15, 1863 |
| Mpc Name: | (78) Diana |
| Adjective: | Dianian |
| Named After: | Diāna (Roman mythology) |
| Epoch: | December 31, 2006 (JD 2454100.5) |
| Semimajor: | 391.9343NaN3 |
| Perihelion: | 310.6863NaN3 |
| Aphelion: | 473.182Gm |
| Eccentricity: | 0.207 |
| Period: | 1548.9222NaN2 |
| Inclination: | 8.688° |
| Asc Node: | 333.582° |
| Arg Peri: | 151.423° |
| Mean Anomaly: | 353.808° |
| Avg Speed: | 18.20 km/s |
| Density: | 1.28 g/cm3 |
| Rotation: | 7.2991 h |
| Abs Magnitude: | 8.09 |
| Albedo: | 0.071 [1] |
78 Diana is a large and dark main-belt asteroid. It was discovered by German astronomer Robert Luther on March 15, 1863, and named after Diana, Roman goddess of the hunt. The asteroid is orbiting the Sun at a distance of 391.934Gm with a period of 4.24 years and an eccentricity (ovalness) of 0.207. The orbital plane is tilted at an angle of 8.688° relative to the plane of the ecliptic. Its composition is carbonaceous and primitive.
Photometric observations of this asteroid during 1986 and 2006–08 gave a light curve with a rotation period of 7.2991 hours and a brightness variation in the range 0.02–0.104 magnitude. Based upon radar data, the near surface solid density of the asteroid is 2.7
. 78 Diana occulted a star on September 4, 1980. A diameter of 116 km was measured, closely matching the value given by the IRAS satellite.Diana is expected to pass about 0.003abbr=onNaNabbr=on from (29075) 1950 DA on August 5, 2150. Main-belt asteroid 4217 Engelhardt (~9 km in diameter) will pass about 0.0017abbr=onNaNabbr=on from (29075) 1950 DA in 2736.