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Jupiter - Introduction

Past the asteroid belt lies the gas giant planets: Jupiter, Saturn, Uranus and Neptune. Because of their proximity to the Sun during the Solar System formation, these planets were able to hold on to their gas envelopes.

Of all the planets, Jupiter is the largest. The most prominent feature on the planet is the swirling clouds and giant red spot.

Jupiter - A Quick Summary: (More information can be found on the Jupiter Fact Sheet and the Jovian Rings Fact Sheet)

Average Distance from Sun: 7.783 x 108 km
Eccentricity of Orbit: 0.048
Average Orbital Speed: 13.1 km/s
Orbital Period: 11.86 years
Rotational Period (equatorial): 9h 50m 28s
Inclination of Equator to Orbit 1.30
Diameter (equatorial): 142,984 km
Mass: 1.899 x 1027 kg

Average Density: 1,326 kg/m3
Escape Speed: 60.2 km/s
Albedo: 0.44

Average Cloud-Top Temperature: -108 C
Atmospheric Composition: 86.2% hydrogen
13.6% helium
0.2% methane
water vapor

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The most remarkable and most visible feature of Jupiter is it atmosphere. We see belts of clouds in intricate patterns. The cloud patterns consist of:

  • Polar regions
  • Temperate regions
  • Tropical regions
  • Equatorial regions

Each region consists of:

  • Belts - darker bands - falling gas - low pressure
  • Zones - lighter bands - rising gas - high pressure

The belts and zone provide the swirling affects. The rotation of Jupiter is the engine that drives all of the motion as well as internal heat. Because of internal heating, the wind speeds can reach up to 500 km/h.

Since its not a solid body like Earth, rotation is differential like our Sun - the center rotates faster than the poles. The image below demonstrates the atmospheric structure of the Gas Giants including Jupiter:

The image above provides much information like gross composition, temperature and altitude.

The Giant Red Spot (GRS) is actually a super storm similar to hurricanes on Earth. Since there are no oceans to control temperature and no land or mountains to alter the wind streams, the GRS is capable of sustaining its energy.

This enhanced Voyager image shows the GRS up close, the patterns of the clouds indicate the storm is rotating counter-clockwise.

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The Interior:

We know very little about the interior of Jupiter but can infer a small core and liquid or gas as the remaining contents because of the lower density of Jupiter compared to Earth. The intense magnetic field allows Astronomers to create a model of the interior:

  • 1000 km thick atmosphere
  • Liquid hydrogen "crust" - very thick
  • Liquid metallic hydrogen "mantle"
  • Rocky core

The liquid metallic hydrogen interior provides the solution for Jupiter's intense magnetic field.

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The Rings:

Saturn is best know for its rings, but it is not the only gas giant to have them. In fact all of the gas giant planets have rings, Jupiter included. The rings are viewable from Earth with only the largest telescopes.

Just like Saturn, Jupiter also has shepherd moons to help maintain the ring structure. While the material of the ring is dusty and icy particles like Saturn, it is though that Io also supplies some of the debris.

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