Asteroid Juno

Juno

Updated June 01, 2013

Juno (3) is the third asteroid discovered in the solar system, named after Juno, the wife of Jupiter. This is one of the main asteroid main belt. Juno was discovered by Carl Ludwig Harding Observatory Lilienthal, near Bremen, September 1, 1804 using a simple 5-cm telescope aperture.
Juno revolves around the Sun in 4.36 years with a semi-major axis of about 400 million km and an eccentricity of 0.26. Juno's orbit changed in 1839, perhaps due to an impact. Images taken in adaptive optics to Mount Wilson Observatory (USA) show that the small planet about 230 km average diameter was completely disfigured by a collision that created a huge crater size 100 km like a bite.
This adaptive optics system has resulted in a remarkably clear view of Juno, reducing interference with the Earth's atmosphere.

Image: The artist representation on the image to the right shows the front, a huge impact crater.
(David A. Aguilar, Harvard-Smithsonian Center for Astrophysics).

NB: The interplanetary space is far from empty, it is littered with dust and matter dating from the creation of the solar system. Asteroids are mainly located in the main belt between the orbits of Mars and Jupiter (between 300 and 600 million km from the Sun). There are hundreds of thousands of objects listed. All objects could have formed a planet in the area but the gravitational perturbations of Jupiter did not permit.

Juno	Characteristics

Dimensions	320x267x200 km
Mean radius	≈233 km
Mass	2.82±0,12×10¹⁹ kg
Rotation period	7.21 hr
Temperature	≈163 K
Aphelion	502.08×10⁶ km
Perihelion	328.87×10⁶ km
Semi-major axis	399.48×10⁶ km
Axial tilt	51°
Orbital period	4.37 a or 1595.4 d
Average orbital speed	17.93 km/s
Eccentricity	0.2568
Inclination to Ecliptic	12.968°
Longitude of ascending node	169.96°
Argument of perihelion	247.93°

Asteroids	Approximate dimensions	Discovery date

Ceres 1	974.6 km	1801
Pallas 2	582×556×500 km	1802
Vesta 4	572.6x557.2x446 km	1807
Hygiea 10	530x407x370 km	1849
Sylvia 87	384x262x232 km	1866
Hektor 624	370x195x195 km	1907
Europa 52	360x315x240 km	1858
Eunomia 15	357x355x212 km	1851
Davida 511	357x294x231 km	1903
Interamnia 704	350.3x303.6 km	1910
Camilla 107	344x246x205 km	1868
Juno 3	320x267x200 km	1804
Cybele 65	302x290x232 km	1861
Hermione 121	268x186x183 km	1872
Euphrosyne 31	255.9 km	1854
Chariklo 10199	248x258 km	1997
Iris 7	240x200x200 km	1847
Psyche 16	240x185x145 km	1852
Daphne 41	239x183x153 km	1856
Kalliope 22	235x144x124 km	1852
Amphitrite 29	233x212x193 km	1854

List of the largest asteroids.

NB: The eccentricity defines the shape of an elliptical orbit, it varies between 0 and 1. 0 for circular orbits. A high eccentricity decreases the minor axis (perihelion) and increases the larger axis (aphelion), but does not change the major axis.