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Jupiter


Next out from the Sun after the asteroids is Jupiter, the king of the planets. Jupiter is the largest and most massive of all the planets with a mass about two and a half times the mass of all the other planets of the Solar system combined!

Jupiter is a "gas giant", a great ball of hydrogen and helium. Some people refer to it as a star that failed - it does radiate twice as much energy as it receives from the Sun (mostly in the infra-red). Jupiter has a relatively small, rocky core composed of iron and silicates, with a temperature of 20,000 degrees C. Around this out to about 46,000 km from the center is a 'sea' of liquid metallic hydrogen (cooling to 11,000 degrees C and 3,000,000 atm). Over this lies an upper 'sea' of liquid molecular hydrogen, and on top of this lies the 1,000 km thick 'atmosphere'.

The colorful bands of Jupiter are from a churning cloud layer (about 150 km thick) composed of ammonia crystals, ammonium hydrosulfide crystals, and water and ice droplets. These clouds are constantly being ripped apart by jet winds of super-hurricane strength. It has been likened to a boiling kettle of colored dyes that cannot be made to blend. The most distinctive feature is the Great Red Spot, a 40,000 km wide super-hurricane that has been going for hundreds of years.

Like the Earth, Jupiter has a magnetic field but (as expected) it is far more intense. The magnetic field extends out some 21.5 million km and is 10,000 times stronger than the Earth's. Anyone passing through the radiation belt (at about 200,000 km out from Jupiter) can expect to take 250,000 rads (500 times the lethal dosage). The movement of the moon Io through this magnetic field generates a current of 5 million ampares (a 100 watt light bulb has a current of 1 ampare). This electrical current is slowly eroding Io away. Gasses from Io's volcanoes break up into charged particles, along with surface matter, to form a growing invisible doughnut-shaped electrical cloud around the planet.

Jupiter is not a peaceful planet.


Orbital Distance:   4.951 AU - 5.455 AU (average 5.203 AU)
Eccentricity:       0.048
Local Year:         4,332.59 days (11.86 years)
Orbital Velocity:   13.06 km/s (average)
Inclination:        1.304°
Local Day:          0.414 day (9h 55m 41s)
Axial Tilt:         3.067°

Diameter:           143,884 km (cloud tops)
Composition:        n/a
Density:            1.33 g/cm3
Mass:               1.90 x 1021 tonnes (317.89 earths)
Gravity:            2.64 G
Escape Velocity:    60.22 km/s
Area:               65,039 million km2
Surface Material:   n/a
Atmosphere:         Hydrogen, helium, ammonia, and methane
Pressure:           Up to 3,000,000 atm
Albedo:             0.43
Temperature:        -130°C (cloud tops)

 


Satellite        Distance       Month         Day   Diameter
Metis          127,960 km     0.295 d     0.295 d      0.003
Adrastea       128,980 km     0.298 d     0.298 d      0.002
Amalthea       181,300 km     0.498 d     0.498 d      0.014
Thebe          221,900 km     0.675 d     0.675 d      0.008
Io             421,600 km     1.769 d     1.770 d      0.286
Europa         670,900 km     3.551 d     3.554 d      0.245
Ganymede     1,070,000 km     7.155 d     7.166 d      0.413
Callisto     1,880,000 km    16.689 d    16.754 d      0.377
Leda        11,094,000 km   238.700 d   254.000 d      0.001
Himalia     11,480,000 km   250.600 d   266.000 d      0.013
Lysithea    11,720,000 km   259.200 d   276.000 d      0.002
Elara       11,737,000 km   259.700 d   276.000 d      0.006
Ananke      21,200,000 km   631.000 d   551.000 d      0.002
Carme       22,600,000 km   692.000 d   597.000 d      0.002
Pasiphae    23,500,000 km   735.000 d   635.000 d      0.003
Sinope      23,700,000 km   758.000 d   645.000 d      0.002

 


Ring       Distance from Jupiter          Width   Thickness
Halo       100,000 km - 122,800 km    22,800 km   20,000 km
Main       122,800 km - 129,200 km     6,400 km       30 km
Gossamer   129,200 km - 214,200 km   850,000 km           ?

 

FAQ - Astronomical Glossary


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