3 Juno
| Discovery | |
|---|---|
| Discovered by | Karl Ludwig Harding |
| Discovery date | 1 September 1804 |
| Designations | |
| (3) Juno | |
| Pronunciation | /ˈdʒuːnoʊ/ JOO-noh |
Named after | Juno (Latin: Iūno) |
| Main belt (Juno clump) | |
| Adjectives | Junonian /dʒuːˈnoʊniən/ |
| Symbol | (historically astronomical, now astrological) |
| Orbital characteristics | |
| Epoch 13 September 2023 (JD 2453300.5) | |
| Aphelion | 3.35 AU (501 million km) |
| Perihelion | 1.985 AU (297.0 million km) |
| 2.67 AU (399 million km) | |
| Eccentricity | 0.2562 |
| 4.361 yr | |
Average orbital speed | 17.93 km/s |
| 37.02° | |
| Inclination | 12.991° |
| 169.84° | |
| 2 April 2023 | |
| 247.74° | |
| Earth MOID | 1.04 AU (156 million km) |
| Proper orbital elements | |
Proper semi-major axis | 2.6693661 AU |
Proper eccentricity | 0.2335060 |
Proper inclination | 13.2515192° |
Proper mean motion | 82.528181 deg / yr |
Proper orbital period | 4.36215 yr (1593.274 d) |
Precession of perihelion | 43.635655 arcsec / yr |
Precession of the ascending node | −61.222138 arcsec / yr |
| Physical characteristics | |
| Dimensions | (288 × 250 × 225) ± 5 km (320 × 267 × 200) ± 6 km |
| 254±2 km 246.596±10.594 km | |
| Mass | (2.7±0.24)×1019 kg (2.86±0.46)×1019 kg |
Mean density | 3.15±0.28 g/cm3 3.20±0.56 g/cm3 |
Equatorial surface gravity | 0.112 m/s2 (0.0114 g0) |
Equatorial escape velocity | 0.168 km/s |
| 7.21 hr (0.3004 d) | |
Equatorial rotation velocity | 31.75 m/s |
Pole ecliptic latitude | 27° ± 5° |
Pole ecliptic longitude | 103° ± 5° |
| 0.202 0.238 | |
| Temperature | ~163 K max: 301 K (+28°C) |
| S | |
| 7.4 to 11.55 | |
| 5.33 | |
| 0.30" to 0.07" | |
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Juno (minor-planet designation: 3 Juno) is a large asteroid in the asteroid belt. Juno was the third asteroid discovered, in 1804, by German astronomer Karl Harding. It is tied with three other asteroids as the thirteenth largest asteroid, and it is one of the two largest stony (S-type) asteroids, along with 15 Eunomia. (Ceres is the largest asteroid.) It is estimated to contain 1% of the total mass of the asteroid belt.