JUPITER 

King of the Gods

Jupiter

General Properties

Cold--the giant planets were cool enough to retain much of the hydrogen present in the nebula from which the Solar System formed.

Powerful gravitational forces--these are strong enough to tear planets apart if they approach too close--that is, closer than the Roche (1849) Limit of about one planetary diameter. This could be the origin of some ring systems.

Great internal pressure--enough to compress hydrogen into a form called liquid metallic hydrogen.

Rapid rotation of this metallic liquid produces strong magnetic fields that trap charged particles from the Sun.
 

Radius: 71,490 km (equatorial); 66,850 km (polar).

Mass: 318 times that of the Earth.

Composition:

Ocean of liquid metallic hydrogen (about 10,000 km below the cloud tops)--density about 4 g/cubic centimeter.

Core probably of iron, rock and water at a temperature of about 30,000 K. The high temperature is caused by the enormous compression in the interior. More energy is radiated by the planet than it absorbs from the Sun.

Rotation: About 10 hours.

Distance from Sun: about 778,330,000 Km (5.2 AU).

Atmosphere

Hydrogen (90 %), helium (10 %). Very similar to the Sun's composition. Trace amounts of methane, ammonia and water.

Pressure at  base of atmosphere about 4 million times Earth's atmospheric pressure. 

Temperature--upper atmosphere about 130 K. Jupiter's rapid rotation 

Zones (light regions) and belts (dark regions) parallel to equator.

Great Red Spot. A cyclonic structure much bigger than the earth.

Moons and Ring System

At least 16.

Galilean Satellites 

Europa--rocky, smooth, lined, few craters.

Io--rocky, highly volcanic (discovered by Linda Morabito of the Voyager 1, 1979 space probe team); few craters.

Outermost: Ganymede, Callisto--rock and ice. These moons were discovered in 1610 by Galileo and Simon Marius (1573-1624). 

Ring system discovered by Voyager I in 1979.

Galileo Probe

On December 7th, 1995 a 339-kilogram Entry Probe was released from the Galileo Orbiter. The Galileo Space Probe was launched on October 18, 1989 from Space Shuttle Atlantis. The Orbiter, which separated from the Entry Probe in July 1995, will remain in orbit about Jupiter for 22 months.

During the first 2 minutes of deceleration the temperature near the probe reached about 12,000 K, which is twice the temperature of the Sun's surface. The deceleration forces were 230 times as strong as the acceleration due to gravity on the Earth.

The probe's radio transmission lasted for 58 minutes. Data were sent to the Orbiter which was 215,000 km (134,000 miles) above. At a depth of 600 km (373 miles) into the atmosphere we presume the probe was destroyed by the extreme environmental conditions of Jupiter's atmosphere. The pressure at that depth is the same as the pressure (22 atmospheres) at a depth of 230 meters below the surface of Earth's ocean.

Jupiter's atmosphere was found to be drier and windier than expected. There was also less helium than expected. One explanation is that the helium, being denser than hydrogen, has sunk towards the core. 

Also, there was a much lower density of complex organic molecules than expected. It is therefore extremely unlikely that any kind of life-form exists in the Jovian atmosphere.