Jupiter

From Acw

Jupiter is the 5th and largest planet of the Sol system. It is one of 4 planets in the Sol system that can be classified as 'Gas Giants'.

Contents 1 Composition and Structure 1.1 Atmosphere 1.2 Internal Structure 2 Moons of Jupiter

Composition and Structure

Atmosphere

The planet's atmosphere is composed largely of Hydrogen (almost 90% by volume) with Helium the only other element present at significiant levels.

Atmospheric composition (by volume, uncertainty in parentheses)

• Major:Molecular hydrogen (H2) - 89.8% (2.0%); Helium (He) - 10.2% (2.0%)
• Minor (ppm): Methane (CH4) - 3000 (1000); Ammonia (NH3) - 260 (40); Hydrogen Deuteride (HD) - 28 (10); Ethane (C2H6) - 5.8(1.5);Water (H2O) - 4 (varies with pressure)
• Aerosols: Ammonia ice, water ice, ammonia hydrosulfide

Jupiter’s visible atmosphere is dominated by banded structures. The white bands are called zones and the dark bands are known as belts. These bands move due to strong zonal jets (eastward and westward currents in the atmosphere) along their boundaries. The zones are anticyclonic, which means they have an eastward jet on the poleward side and a westward jet on the equatorward side. The belts are cyclonic, which means they rotate the opposite way. The colors of the belts and zones vary with time. The origin of the colors and how they respond to the winds are uncertain. The major cloud constituents, ammonia, H2S, and water, are colorless, but elemental sulfur, phosphorus, and organic compounds could combine in trace amounts to form the muted brown colors that characterise the appearance of the planet.

Weather patterns in Jupiter's atmosphere can last for centuries, largely because the planet has no topography, meaning its atmosphere merges smoothly with the planet’s fluid interior, and also because it has no appreciable equator-to-pole temperature gradient. The most famous weathern pattern on Jupiter is the Great Red Spot (GRS), an anti-cyclonic vortex (high pressure system) 17,000km across and 12500km high.

Internal Structure

In 2149 UISA scientists launched a probe from their research base on Ganymede to finally determine, once and for all, the nature of the interior structure of Jupiter. Up until that time, the only available data came from gravity and magnetic field measurements and it was uncertain whether Jupiter contained any solid matter at all, or was simply a ball of homogenous gas, with density gradually increasing towards the centre of the planet. The data the probe sent back provided the first ever accurate picture of Jupiter's interior. Jupiter's interior can be divided into three discrete layers. Working from the outside towards the interior, these are

• Liquid Zone: Composed of hydrogen, intially in a gasesous state and then becoming liquid as one moves towards the interior. Instead of a clear boundary between these different phases of hydrogen, there is smooth gradation from gas to liquid as one descends.

• Metallic Hydrogen Zone: Makes up around 78% of the radius of Jupiter (around 100,000km in depth). This zone could be considered somewhat equivalent to the mantle zone on tectonically active rocky planets, with the Liquid Zone floating on the surface of the Metallic Hydrogen Zone.

• Core Zone: The centre of Jupiter consists of a solid matter component, composed largely of iron, with a diameter of about 24,000km. Despite the intense temperatures and pressures at Jupiter's centre, the core maintains a perpetual solid state.

Within each of the zones there is transistional change and variation but the boundaries between each of the zones are sharp and precise.

The probe also confirmed that the temperature and pressure inside Jupiter increase steadily toward the core. At the boundary of the Metallic Hydrogen zone, the measured temperature was 10,000 K at a pressure of 200 GPa. At the boundary of the Core Zone, measured temperature was 36,000 K with pressure values of 4,130 GPa.

The UISA initially delayed the general release of the probe data, hoping they could somehow turn the knowledge to their advantage, perhaps even using it to colonise Jupiter proper. When it became apparent that such as task would be extremely difficult and tremendously exorbitant (one estimate placed the total cost somewhere around 3000 billion dollars), the UISA government abandoned the idea and allowed the scientists involved in the project to publish their data in the journal Science.

Despite the UISA government's claims that the project never went ahead, rumours persist to the modern day that the UISA did actually establish a base at Jupiter's core but no real evidence has ever come to light. A number of scientific reports on the subject (both government and independantly commissioned) have suggested that the task would be impossible no matter how much money was invested, due to the massive temperatures and pressures involved.

Moons of Jupiter

Jupiter has a total of 63 moons but most of these are less than 10km in diameter. Only 4 of Jupiter's moons are large enough to be suitable for human colonisation

• Io - Italian colony
• Europa - Italian colony
• Ganymede - UISA colony
• Callisto - French colony