ch 12-1 Saturn

Saturn

• 6th

• 2nd largest

• less than 1/3 of Jupiter’s mass

• no solid surface

• less sense

• has most planets

• bright rings

what is the radius of Saturn?

• 600,000km

what is the mass of Saturn?

• 5.7 × 10²⁶

what is the density of Saturn?

• 700 kg/m³

  • less than water

  • least dense planet

would Saturn float if placed in a large enough body of water?

• yes, lower mass results in lower interior pressure, gasses less compressed than Jupiter

Saturn’s rotation

• rapid and differential, enough to flatten Saturn considerably

  • atm. rotates at different speeds depends on latitude

  • 10.5 hours

what does atm. rotation period determined by?

• tracking weather features

what does Saturn’s lower density cause?

• it to be flatter

Saturn’s rings

• very prominent; wide but extremely thin

  • maybe debris from shattered moons

  • rocky and icey particles

  • young 10-100 Ma

Saturn’s rapid speed

• oblate spheroid

  • bulges at equator

  • flatten at poles

who first observed Saturn’s rings?

• Galileo

  • 2 lateral components

    • “ears”

      • triple bonded

where do Saturn’s ring lie?

• in the equatorial plane

  • as Saturn moves along its orbit, angles at which the rings are illuminated and which we view them vary

what did Huygens discover?

• Saturn was surrounded by a thin, flat, independent ring

  • ecliptic plane

  • space between planet is thick

how do the view of Saturns rings change?

• disappears from Earths view every 10-15 years

• appearance changes as tilted plane

what is Saturn’s atmosphere composed of?

• mostly molecular hydrogen 92.4%, helium 7.4%, methane 0.2%, and ammonia 0.002%

  • helium fraction is much less than on Jupiter

  • chaotic gas envelope

Saturn’s surface

• lack solid surface

• transition to liquid interior under high pressure

what does Saturn’s atmosphere show?

• zone and distant horizontal band structures (parallel to equator), but coloration is much more subdued than Jupiter’s

how does Saturn’s atmosphere form?

• in layers with ammonia crystals on top

  • ammonia hydro surface at lower depth

Saturn’s bands

• are more subdue, wider, and colorful

  • organic and smog likely due to increased sulfur content

what direction do zonal winds flow?

• east → west

• this true-color image shows the delicate coloration of the cloud patterns on Saturn

what is Saturn’s atm. similar to?

• similar to Jupiter’s except pressure is lower

what does Saturn’s atm. composed of?

• 3 cloud layers

  • cloud layers are thicker (spread further apart) than Jupiter’s; see only top layer (butterscotch appearance)

what is the total thickness of all 3 cloud layers?

• 200km thick

  • reason for difference in Saturn’s weaker gravity

  • butterscotch hue

what are the three cloud layers?

1. ammonia ice clouds

   • highest layer

   • coldest layer

2. ammonium hydrosulfide clouds

   • middle layer

   • made from ammonia + sulfur compounds

3. water clods

   • deepest major cloud layer

   • warmest of the three

what is zonal flow?

• wind patterns on Saturn are similar to those on Jupiter

  • 18,000 km/h

  • same flow as rotation

  • bands parallel to equator

  • faster and less east-west alterations

what can Jupiter-style “spots” can turn into?

• large storms on Saturn, then dissipate relatively quickly

what are “spots”?

• massive storms, spots, hexagonal features

• large spots are rare

• roughly 30 years during planets northern summer

“great white spots”

• planet encircling storm that occurs 1 every Saturn year (~29.5 Earth years)

  • start as spiral vortices

  • explosions last long but dissipates quick

giant vortices exist at both poles of Saturn, apparently due to?

• jet streams

• rotate high above cloud tops

giant vortices at north and south poles

• whorl pools → polar vortices

  • hurricane like cyclone

  • unique long live hexagonal jet stream

Saturn’s interior and magnetosphere

• interior structure similar to Jupiter’s

• dense fuzzy core of rock and ice → 20 x mass of Earth

  • surrounded by liquid hydrogen layer

what does Saturn also radiate?

• more energy than it gets from the Sun, but no because of cooling

Why does Saturn radiate more energy than it receives from the Sun?

• Because helium condenses into droplets and falls deeper into the planet, releasing gravitational energy as heat.

What is helium rain?

• The process in which helium separates from hydrogen, forms droplets, and sinks deeper into Saturn.

How does helium rain heat Saturn?

• As helium droplets fall inward, gravitational compression releases energy as heat.

What role does Saturn's gravitational field play in helium rain?

• It pulls helium droplets inward, releasing heat through gravitational compression.

extra heat on Saturn

• at higher temps. and high pressure, found Jupiter’s interior, liquid helium dissolves in liquids

• inside Saturn where internal temp is lower the He doesn’t dissolve so easily and tends to from droplets instead

Saturn’s Magnetosphere

• strong magnetic field, but only %5 as strong as Jupiters

• extends ~1 million km toward the sun and large enough to contain the planets ring system and innermost 16 small moons

• emits radio waves, reflected from Earths ionosphere

what does Saturn’s Magnetosphere create?

• Aurorae

  • sometime from spirals

what was thought about the magnetospheres tilt?

• needs tilt to sustain currents through liquids metal deep in planet

  • without tilt, current dies