(3) Juno

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( 3) Juno is an asteroid of the main asteroid belt. He was discovered on September 1, 1804 by Karl Ludwig Harding, the third asteroid and after Juno, the highest Roman goddess named. Juno was initially classified as a full-fledged planet after its discovery as well as the recently discovered asteroid ( 1) Ceres and (2) Pallas. Only after 1847 was a distinction between asteroids and planets. Your path has been calculated in the 1810s in Göttingen under the direction of Carl Friedrich Gauss by Friedrich Ludwig Wachter.


Juno moves at a distance of 1.98 ( perihelion ) and 3.36 ( aphelion ) AE in 4.36 years of the sun. The orbit is inclined 13.0 ° to the ecliptic, the orbital eccentricity is 0.26.


Juno has an average diameter of about 267 km. Their mass was determined to 2.82 × 1019 kg. It has a relatively bright surface with an albedo of 0.24. While the opposition they reached an apparent magnitude of up to 7.7 mag and is it one of the brightest asteroids in the night sky. In about 7.2 hours to rotate around its own axis.

In the year 1996 ( results published in 2003) Juno has been thoroughly investigated with the aid of a 2.5 -meter reflecting telescope of the Mount Wilson Observatory and adaptive optics. It turned out that Juno is an irregular celestial body, whose shape is reminiscent of a potato. The images in the infrared region show a 100 km wide impact crater, which probably originated geologically short time ago. Spectroscopic studies indicate that Juno could be the origin of ordinary chondrites body, a common group of stony meteorites, which are composed of iron-containing silicate compounds such as olivine and pyroxene.

Juno was the first asteroid in which an occultation was observed. On February 19, 1958 Juno pulled over right in front of a faint star and darkened it for several seconds. Since then, several occultations have yet been observed by Juno. The size of Juno was about 290 × 245 km determined from these observations.