Jupiter, the largest planet in the solar system is a gas giant planet made up to 93% hydrogen and 7% helium. It represents 71% of the total mass of the planets of the solar system. This is the fifth planet from the Sun, after Mercury, Venus, Earth and Mars. It is named after the Roman god Jupiter. Visible to the naked eye in the night sky, Jupiter is the fourth brightest object after the Sun, Moon and Venus. From time to time, Mars appears brighter than Jupiter and Jupiter may appear brighter than Venus. Like the other gas planets, the winds of nearly 600 km/h, run through the upper layers of the planet. The famous Great Red Spot, well known to fans, is an area of pressure has long been observed. Jupiter gives off more energy into space than it receives from the Sun (mass = 318 times the Earth). Jupiter has acted as a shield, protecting life on our planet. If Jupiter was not present, the bombardment of asteroids on Earth would be 1000 times more common. Meteorite bombardment would take place every 60,000 years and life would have lacked stability to flourish, we would stage filter. The presence of a giant planet is proving vital in a solar system for objects destructors are mainly attracted by the giant planet. Jupiter is surrounded by more than 60 moons. The first of Jupiter's moons were discovered in 1610. Galileo Galilei discovered at that time the four largest satellites of the Jovian system Io, Europa, Ganymede and Callisto. Thanks to space probes, we have a more complete view of the Jovian system. This is the series of Voyager, which was discovered in 1979, Metis, and Thebe Adrastea. Before the space age, astronomers have discovered Amalthea (1892), Himalia (1904), Elara (1905), Pasiphae (1908), Sinope (1914), Lysithea and Carmi (1938), Ananke (1951), Leda ( 1974), Themisto (1975), Callirrhoe (1999). In 2000, ten new moons were added, bringing the number to 28. In 2001, 11 new moons enrich our knowledge. In 2003, 23 new satellites are added to the list in 2006, 63 were known moons of Jupiter, most of which less than 9 km in diameter.
Video : Look turning Jupiter as the spacecraft, New Horizons flew by Jupiter in 2007. We see into the atmosphere of the largest planet in the solar system, the cloud bands alternating more or less clear, and huge storms swirling that appear as ovals. The diameter of Jupiter is about 11.2 times that of Earth and the giant turns on itself in 9 hr 55 min 27.3 s.
nota : "A planet is a celestial body that is in orbit around the Sun, which has sufficient mass for its gravity to overcome the cohesive forces of the solid body and maintain hydrostatic equilibrium (spherical), which eliminated any body moving in an orbit close. " This definition was approved August 24, 2006, at the 26th General Assembly of the IAU (International Astronomical Union) by a show of hands of about 400 scientists and astronomers, after ten days of discussions.
Jupiter (Zeus in Greek) is by far the biggest planet of the solar system its size is 318 times superior to that of the Earth. It is visible all night long when Jupiter and the Sun are set in the sky with regard to the Earth. It is at this moment there that it is in closer of the Earth. These oppositions follow each other in intervals of 13 months. Already by means of small objectives, we can discern the strong flattening of the planet. On the surface of Jupiter, we observe the red spot, in the south zone, in a latitude of 35 °. While the Earth and the telluric planets are solid objects constituted by a mixture of iron and silicates, essentially surrounded with a little gas, Jupiter is essentially constituted by hydrogen and by a little helium, as the Sun.
Jupiter emits twice more energy than it receives from it from the Sun. The nucleus formed by rocks and by ice is doubtless surrounded by a liquid coat. The Galileo probe penetrated into the atmosphere of Jupiter during one hour in the middle of 320 kph winds and showed that the hydrogen dominated and that the temperature increased very fast in depth. Jupiter is endowed with a system of rings, as all the huge planets, constituted by small rocky fragments assembled in a disk in rotation, wide and very fine.
nota: A planet is more brilliant than a star, it shines with a constant brightness among stars. Planets sparkle less than stars. To identify planets it is necessary to get acquainted with the stars of the zodiac because they follow the ecliptic.
Structure of Jupiter
We do not know well the structure of Jupiter but the giant planets were probably formed by accretion of hydrogen and helium gas around a core of rock and ice. Jupiter with a mass 318 times that of Earth, probably has a rocky core (silicates and iron) the size of Earth and about 10 times the mass of Earth. This rocky heart could bathe in hydrogen and helium liquid at a temperature of about 16,000 K and a pressure of about 80 million atmospheres. The global composition of Jupiter based on hypothetical models. The rocky core is so small compared to the size of the planet (7%) that scientists omit this core talking gaseous planet. In fact 93% of the volume of Jupiter is made of gas, again it is not necessary to see gas of Jupiter as our gas of our atmosphere but rather as a highly compressed liquid by gravitational force of the planet and extremely dense. At center of the planet, the metallic hydrogen atoms are broken by the enormous pressure, it is called then ionized hydrogen. It is only up to the surface that this hydrogen gradually becomes liquid and gaseous. There would be no boundary between free states of the hydrogen layers, transition would gradually.
To surface from interior, we descend gradually into a thick fog more and more dense and opaque until a sea of liquid hydrogen, also more and more dense and hot to finish in metallic hydrogen always more and more dense and hot (16000 K), to the rocky core which would it to a temperature of the order of 25,000 K and a pressure of about 80 million atmospheres. Spectroscopy carried by space probes has broken down the layers of the atmosphere of Jupiter. Jupiter is composed of 86% hydrogen (H) 14% helium (He), a small amount of methane (CH4), ammonia (NH3) and water vapor (H2O).
Image : At center, the small rocky core surrounded by a huge sea of metallic hydrogen and then liquid then towards surface helium is mixed with hydrogen in a gaseous atmosphere. The global composition of Jupiter based on speculative models.
Great red spot of Jupiter
Jupiter possesses an enormous cyclone on its surface, the famous big red spot. It was discovered by Cassini, 300 years ago. This cyclone measures 12 000 x 25 000 km; twice the planet Earth. Besides its gigantic size, its life cycle remains unexplained. Indeed, a simple cyclone should evolve in the time and possibly to disappear completely, while in three centuries of observation, the spot that little changed. The mechanism in its origin stays a scientific enigma. Jupiter is the defender of our system. Jupiter played the role of shield, defender of the life on our planet. If Jupiter was not present, the bombardment on Earth would be 1000 times as frequent. A bombardment would take place every 60 000 years and the life would have missed stability to bloom, we would be at the bacterial stage there. The presence of Jupiter allowed the Earth to become a planet where abound thousands of alive sorts. The presence of a huge planet shows itself of a vital importance in a solar system (see exoplanets).
Image : This against the moved closer photography realized to Voyager 1 on June 6th, 1979, (stressed colors). For more than a century, the astronomers thought that the Big Red Spot was the biggest observable structure on the surface of Jupiter. Recently images of the vessel Cassini revealed something of at least so big: the Big Spot Sinks. The destructive objects are mainly attracted by the huge planet Jupiter.
Moons of Jupiter
Around Jupiter, constituted a real solar system in miniature. A lot of matter would have be needed so that the heart of Jupiter ignites. More than 60 satellites revolve around him, they are all situated on the equatorial plan, as the planets around the Sun.
Image : Four Galilean moons of Jupiter, from top to bottom: Io, Europe, Ganymede and Callisto.
The ballet of its four main satellites (Io, Europe, Ganymede, Callisto) can observe with a simple pair of binoculars 10x50, an instrument of 60mm of diameter will reveal two wide brownish belts, parallel to the equator of the huge planet.
Here 4 moons Galileans. Jupiter possesses more than 60 known natural satellites names of which are pulled by the Greek mythology.
Image : On this photography, below to the left, we can see Ganymede who walks past Jupiter.
The second last passage of the comet Shoemaker-Levy 9 closer to Jupiter (40 000 km), took place in July 1992. Periodic comet passed so close to the huge planet she broke into twenty pieces. Two years later, in the following passage in July 1994 for 7 days fragments crashed into Jupiter in producing gigantic lightning. The event has been the subject of extensive media coverage, it was observed several weeks, by almost all observatories in all wavelengths from ultraviolet to infrared. The comet was spotted March 24, 1993, on a photograph taken with the 40 cm Schmidt telescope of the Palomar Observatory in California. Between 16 and 22 July 1994, the pieces of the comet crashed into gas giant at a speed of ≈ 60 km / s. The shocks have brings out a cloud of matter at the location of impact.
Image : Comet Shoemaker-Levy 9 fractionated by the gravitational force of Jupiter as seen by the Hubble Space Telescope in May 1994. Traces of impacts were visible for several months. One balls of fire of the giant comet is mounted about 3000 km above the surface of Jupiter.