Jupiter, the largest planet of our Solar system is the fifth planet from the Sun. It is over 11 times the size of Earth and is so large that it can fit 1,400 Earths. It is assumed that if Jupiter was larger, it might have been a sun. After the Sun, the Moon and Venus, Jupiter is the fourth brightest object in the sky. It has been known since prehistoric times as a bright “wandering star”. Jupiter is a very stormy planet and most of the storms seem to never end. Different cloud formations and storms in the atmosphere make Jupiter a very colorful planet.
Jupiter has 1400 times the volume of Earth however the mass is only 318 times more. Hence, the mean density of Jupiter is approximately one-fourth that of Earth, signifies that the Planet Jupiter must consist of gases rather than the metals and rocks of which the Earth and other inner planets are composed.
Jupiter has the largest planetary atmosphere in the Solar System – expanding over 5000 km in altitude. Major part of atmosphere is molecular hydrogen (H2). Samples tested by the Galileo probe indicated 89.8 percent molecular hydrogen, 10.2 percent helium, minor amounts of methane, ammonia, hydrogen deuteride, ethane, water, ammonia ice aerosols, water ice aerosols, ammonia hydrosulfide aerosols. The core of the planet must have essentially the same composition taking into account the observed low density. It seems that, this huge world must be made mostly of the two lightest and most abundant elements in the universe, a mixture resembling that of the Sun’s and other stars’.
Jupiter’s clouds have bright colors, which are probably the result of subtle chemical reactions of the trace elements in Jupiter’s atmosphere. It possibly involves sulfur whose compounds take on a wide diversity of colors, but the details are unidentified. Jupiter’s atmosphere also features large storm structures; one of them is famous Great Red Spot (GRS). The GRS is an oval about 12,000 by 25,000 km, which is very big and is enough to hold two Earths. Other smaller but comparable spots have been discovered for decades. Infrared observations and the direction of its rotation specify that the GRS is a high-pressure region and its cloud tops are considerably higher and colder than the neighboring regions. However it is not known yet, how such formation can remain active for so long.
Internal structure of the Jupiter
Most likely Jupiter has a core of rocky material amounting to somewhat like 10 to 15 Earth-masses. Over the core lies the bulk of planet’s mass in the form of liquid metallic hydrogen. Liquid metallic hydrogen on Jupiter has ionized protons and electrons just like the interior of the Sun, however at a much lower temperature. Due to high temperatures and pressure inside of Jupiter, hydrogen is kept in a liquid form, not a gas. Hydrogen is an electrical conductor and the cause of Jupiter’s magnetic field. This layer most likely also includes some helium and traces of various “ices”. The outermost layer consists mainly of ordinary molecular hydrogen and helium that is liquid in the interior and gaseous outwards. The atmosphere we can observe is only the very top of this layer. Water, carbon dioxide, methane and other molecules are also there but in tiny amounts.
It is assumed that the Jovian magnetic field is generated deep within the layers of the planet. At the Jupiter’s surface, this field is 14 times stronger than Earth’s. Its polarity is the opposite of Earth’s so that a terrestrial compass at Jupiter would point south. This Magnetic field is accountable for the huge belts of trapped charged particles which circle the planet out to a distance of 10 million km. It is approximately ten times as strong as the Earth’s Van Allen radiation belts and holds mysterious high-energy helium ions from an unknown source.
Jupiter spins faster than any other planet
Jupiter rotates on its axis every 9.9 hours, compared with 24 hours for Earth. This rapid spin causes a bulge at its equator and flattening at the poles, making the planet roughly about 7 percent wider at the equator than at the poles. Jupiter makes a complete orbit around the sun in 11.9 Earth years. It completes the orbit around the sun at a mean distance 5.2 times greater than one astronomical unit.
NASA’s Voyager 1 spacecraft discovered Jupiter’s three rings. The first ring, which is the main ring is flattened. It is roughly about 20 miles thick and more than 4,000 miles wide.
The second ring, called the halo, is roughly 12,000 miles thick. The main ring and halo, both are composed of small, dark particles.
The third ring, called the gossamer ring is perhaps made up of dust particles less than 10 microns in diameter. It extends to an outer edge of about 80,000 miles from the center of the planet and inward to about 18,600 miles.
Jupiter has at least 63 moons. The four largest moons of Jupiter, which were discovered by Galileo himself, are known as Io, Europa, Ganymede, and Callisto. These moons are more commonly known as the Galilean satellites.
Io is the most volcanically active body in our solar system. The sulfur emitted by these volcanoes emit gives Io a blotted yellow-orange appearance. As this moon orbits Jupiter, the planet’s immense gravity results in ‘tides’ in Io’s solid surface which rise 300 feet (100 meters) high, creating enough heat for volcanic activity.
The frozen crust of Europa is constituted mostly of water ice, and it might have a liquid ocean holding twice the water Earth does. Icy oceans might also be present under the crusts of Callisto and Ganymede.
Callisto has the lowest reflectivity, of the four Galilean moons. This implies that its surface might have dark, colorless rocks.
Potential prospects for life on Jupiter
After Mars, the Jovian system is probably the place in the solar system to sport life. Although the planet itself cannot have life and most of its moons cannot either, the four moons discovered by Galileo present some hope. Especially, the icy moon Europa is the leading candidate for life. Many NASA scientists expect with strong evidence that an ocean is concealed under the moon’s solid and icy surface. NASA is currently working to find a way to send a probe to Europa that would finally dig deep beneath its surface. And if life does not exist on Europa, the larger Jovian satellites Callisto and Ganymede have an environment potentially suitable for upcoming human colonization.
Jupiter was primary visited by Pioneer 10 in 1973 and then by Pioneer 11, Voyager 1, Voyager 2 and Ulysses. The spacecraft Galileo orbited Jupiter for eight years and is still regularly observed by the Hubble Space Telescope.