The list goes on of the moons of Jupiter, in late 2011, it rose from 65 to 67.
In 1610 Galileo announced the discovery of the first moon, the four largest of Jupiter.
With his new glasses, he can see Io, Europa, Ganymede and Callisto, turn around the largest planet in the solar system.
SSince the number of known moons of Jupiter has greatly increased.
On January 29, 2012, a research team led by Scott S. Sheppard of the Carnegie Institution of Washington, announced the discovery of two new moons, the 66th and 67th moons are named interim S/2011 J1 and S/2011 J2.
The peculiarity of its moons is that they orbit around Jupiter in the opposite direction of rotation of Jupiter, they are retrograde.
These are very small bodies, compared with the large moons, their diameter is only a few kilometers.
Both moons have a highly elliptical orbit.
S/2011 J1 is an average distance of 20 million km of Jupiter, S/2011 J2 to 23 million km.
This observation was made by the Magellan 6.5-meter telescope located at Las Campanas in the Andes in Chile, known for the quality of the sky.
The two newly discovered moons belong to the category of so-called irregular satellites of Jupiter, of which 59 are currently known. | | The irregular satellites are characterized by the fact that their orbits are elliptical and located at great distances from their planets. In addition they are often highly inclined with respect to the equatorial plane of the planet.
The four giant planets of the solar system, ie Jupiter, Saturn, Uranus and Neptune have many irregular satellites.
Astronomers assume that these moons were originally asteroids that were captured by the gravitational field of the giant planets.
Over the past decade, dozens of irregular satellites were discovered, there are currently a total of 172 known moons around the planets of the solar system.
We owe these discoveries to many telescopes with CCD sensors, many light-sensitive, have been significantly improved.p> * The orbits of the satellites of Jupiter are represented on this graph.
The small purple circles in the middle of the image are the orbits of the four large moons, which are nearly circular.
The orbits shown in green, red and blue are the orbits, highly elliptical, irregular moons. | | 
* The orbits of Jupiter, stretch 400 000 km to 30 million km from the giant Jupiter. |
| | * The four Galilean moons of Jupiter (left). From top to bottom: Io, Europa, Ganymede and Callisto. The ballet of its four main satellites (Io, Europa, Ganymede, Callisto) can be observed with a simple pair of binoculars 10x50, an instrument of 60mm diameter reveal two broad belts brownish, parallel to the equator of the giant planet . Jupiter has more than 60 known moons whose names are drawn from Greek mythology. Moon | mean diameter | mass | | | | | | Ganymede | 5 262,4 km | 1,48 x 1023 (kg) | | Callisto | 4 820,6 km | 1,08 x 1023 (kg) | | Io | 3 643,2 km | 8,93 x 1022 (kg) | | Europa | 3 121,6 km | 4,8 x 1022 (kg) |
* In this photograph (right), bottom left we see Ganymede passing in front of the monster gaseous Jupiter. | |  |
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