PES 105        Fall 2001 Previous Lecture General Astronomy I Next Lecture

Lecture Notes:

Jupiter

text: Chapter 9: Section 9.1

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Introduction and General Properties

Here is a good link for information about the Jupiter: http://seds.lpl.arizona.edu/billa/tnp/jupiter.html

Here is another good link with information, pictures and animations about Jupiter: http://www.planetscapes.com/solar/eng/jupiter.htm

Here is a link with pictures of Jupiter: http://antwrp.gsfc.nasa.gov/apod/index/Jupiter.html

NASA Galilio spacecraft home page - (great picture of Io): http://www.jpl.nasa.gov/galileo/index.html

Jupiter is the largest planet

mass = 318 x Earth

volume = 700 x Earth

albedo = 0.52 . . . . cloud covered

density = 1.3 g/cm³ . . . much lower than terrestrial planets

=> more like gas or liquid

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Motions

orbit:

• orbital period = 11.9 years

rotation:

• rotation period = 10 hours
  • very fast !!
  • clouds at the equator are moving at 45,000 km/hr
  • compare to 1670 km/hr on Earth, 1190 km/hr = speed of sound in air
• equator rotates faster than poles (by about 5 minutes)
  • called "differential rotation"
  • only possible on gas or liquid planet
• fast rotation flattens out the sphere at the poles - bulges at equator
• not tilt of rotation axis => no seasons

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Interior

observe STRONG magnetic field

since it rotates quickly, expect liquid inside

magnetic axis is tilted about 11 degrees from rotation axis with South magnetic pole on top

higly differentiated

(liquid metallic hydrogen requires 3 million atmospheres of pressure - has been observed in labs on Earth)

Figure 9.2 also show a cross section of Jupiter. [Link to Figure 9.2]

source of heat inside

• planet emits twice the energy received from the Sun
• left over energy from formation
  • (gravitational potential energy)
• big planet => cools slowly

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Surface

Where ?

What ?

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Atmosphere

Composition: (from spectroscopy)

• hydrogen - 86 %
• helium - 14 %
• others - < 1 %

similar to composition of original cloud that solar system formed from

=> very little change in atmosphere

 

Ciculation

from:

• convection
  • mainly internal heat rather than Sun
• rotation

expect cells to form - somewhat like Earth - but fast rotation stretches them into bands

• belts
  • dark
  • regions of low pressure
  • falling air
• zones
  • light
  • regions of high pressure
  • rising air

  Figure 9.3 shows this concept in some detail. [Figure 9.3]

   

  different colors arise from different temperatures and compositions

  • [often more ammonia in light regions]

Great Red Spot

• similar to storm on Earth
• about twice the size of Earth
• rotates once in 6 days
• at least 300 years old
• high pressure region (rising air) [in Southern hemisphere]

  Figure 9.1 shows the Great Red spot. [Link to Figure 9.1]

  This video shows the Great spot in motion: http://www.planetscapes.com/solar/cap/jup/vjupitr3.htm

overall: very complex circulation

Figure 9.4 shows some of the complex wind patterns. [Link to Figure 9.4]

This animation also shows the rotation, belts, zones and Great Red Spot: http://www.planetscapes.com/solar/cap/jup/vjupitr1.htm

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History

4.5 billion years ago	planetisimals collide forming large protoplanet
	collects gasses and grows rapidly to form planet
	eventually no more gasses to collect
	.
since then	no changes

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Moons:

16 moons

• mainly ice and rock
• no atmospheres
• all in synchronous orbit

  

Galilean Satellites

note: Jupiter is heat source

Figure 9.7 shows the four Galilean satellites. [Link to Figure 9.7]

Io

in orbital resonance with Europa

orbital period of Io = 1/2 period of Europa

this leads to strong tidal forces on Io

OPTIONAL MATERIAL:

strong tidal forces heat Io

• causing volcanoes of sulfur compounds [observed by spacecraft]
  • Figure 9.8 shows the volcanoes on Io. [Link to Figure 9.8]
• surface has few impact craters => constantly evolving
• This animation shows Io (note the sun in the distance when on the shadowed side of the moon): http://www.planetscapes.com/solar/cap/jup/viojup1.htm

Europa

• few craters => surface is < 1 million years old
• very smooth surface
• ice covered (about 6-10 miles thick) [from density measurements]
• possibly water underneath ice

  tidal forces may stretch the moon causing

• many cracks
  • Figure 9.9 shows the cracks of Europa. [Link to Figure 9.9]
• flowing of ice (no craters observed)
• heat ?
• [water + heat = life ???]
• observe weak magnetic field

  Ganymede

• largest moon in Solar System
  • slightly larger than Mercury
• covered by thick ice layer (< 1000 km)
• weak magnetic field (water inside ?)
• surface:
  • cratered areas - old
  • grooved areas - younger
    • like rows of mountains => plate tectonics ?

  Callisto

• many craters => old surface
• ice covered (thick layer)
• possible weak magnetic field ?:
• layer of dark dust over ice

Outer moons

captured asteroids

Ring

• single ring
• thin
• dark
• very small particles (< 1mm)

Figure 9.6 shows the ring. [Link to Figure 9.6]

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