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Juno (asteroid)

3 Juno Juno symbol.svg
Juno 4 wavelengths.jpg
Juno seen at four wavelengths with a large crater in the dark (Hooker telescope, 2003)
Discovery
Discovered by Karl Ludwig Harding
Discovery date September 1, 1804
Designations
MPC designation (3) Juno
Pronunciation /ˈn/
Named after
Juno (Latin: Iūno)
none
Main belt (Juno clump)
Adjectives Junonian /ˈnniən/
Orbital characteristics
Epoch JD 2457000.5 (9 December 2014)
Aphelion 3.35293 AU
(502.050 Gm)
Perihelion 1.98847 AU
(297.40 Gm)
2.67070 AU
(399.725 Gm)
Eccentricity 0.25545
4.36463 yr
(1594.18 d)
Average orbital speed
17.93 km/s
33.077°
Inclination 12.9817°
169.8712°
248.4100°
Proper orbital elements
2.6693661 AU
Proper eccentricity
0.2335060
Proper inclination
13.2515192°
Proper mean motion
82.528181 deg / yr
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 (320×267×200)±6 km
(233 km)
216 000 km2
Volume 8 950 000 km3
Mass 2.67 ×1019 kg
Mean density
3.20 ± 0.56 g/cm³
0.12 m/s2
0.18 km/s
7.21 hr (0.3004 d)
Equatorial rotation velocity
31.75 m/s
Albedo 0.238 (geometric)
Temperature ~163 K
max: 301 K (+28°C)
Spectral type
S-type asteroid
7.4 to 11.55
5.33
0.30" to 0.07"

Juno, minor-planet designation 3 Juno in the Minor Planet Center catalogue system, is an asteroid in the asteroid belt. Juno was the third asteroid discovered, on 1 September 1804 by German astronomer Karl L. Harding. It is the 11th-largest asteroid, and one of the two largest stony (S-type) asteroids, along with 15 Eunomia. It is estimated to contain 1% of the total mass of the asteroid belt.

Juno was discovered in 1804 by Karl Ludwig Harding. It was the third asteroid found, but was initially considered to be a planet; it was reclassified as an asteroid and minor planet during the 1850s.

3 Juno is named after the mythological Juno, the highest Roman goddess. The adjectival form is Junonian (jūnōnius).

With two exceptions, 'Juno' is the international name, subject to local variation: Italian Giunone, French Junon, Russian Yunona, etc. Its planetary symbol is ③. An older symbol, still occasionally seen, is ⚵ (Old symbol of Juno).

Juno is one of the larger asteroids, perhaps tenth by size and containing approximately 1% the mass of the entire asteroid belt. It is the second-most-massive S-type asteroid after 15 Eunomia. Even so, Juno has only 3% the mass of Ceres.

The orbital period of 3 Juno is 4.36578 years.


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