Jovian Planets Flashcards
What are the Jovian planets?
Jupiter, Saturn, Uranus, Neptune
What are the cores of Jupiter and Saturn like?
Rocky (10 earth masses)
Describe atmospheres of Jupiter and Saturn
Extensive
Made of hydrogen and helium( similar composition to sun)
Describe Uranus and Neptune atmosphere
Extensive atmosphere of gaseous hydrogen
Why is there no liquid or metallic hydrogen in Uranus and Neptune?
Pressure not high enough (instead inner parts made of water, Nathan’s and ammonia ices[hot dense fluid])
Define the frost line
The distance from a star at which it is possible for hydrogen compounds to condense into ices
Where is the frost line in our solar system?
Between present day orbits of Mars and Jupiter
Why are rocky terrestrial planets within the frost line?
Only metals and rock can condense inside the frost line
What happens outside frost line?
Hydrogen ice compounds available to build planets
•more solid material available, icy planetesimals, more massive cores
•able to capture and hold hydrogen and helium gas
•planets grow rapidly and attract more gas
What happens to density of material as distance from sun grows?
Decreases
What are the 3 cloud layers of jupiters atmosphere?
•ammonia
•ammonium hydrosulfide
•water
How many cloud layers do Uranus and Neptune have?
1 (methane)
What produces the colours of the Jovian planets?
Clouds
How do the upper atmospheres of Neptune and Uranus different from Jupiter and Saturn? What effect does this have?
Much colder meaning methane precipitates and forms clouds
Why does the Coriolis force occur?
The actual ground speed of a rotating sphere varies with latitude
Explain Coriolis force?
Temperature differences between poles and equator leads to north-south/south-north airflows
Airflow perpendicular to rotation deflected by Coriolis force
What forms bands on Jupiter?
•velocity at jupiters equator very fast so much stronger Coriolis effect
•dynamic weathe: strong winds so bands and storm stable over decades
Why does Jupiter have no seasons?
No axis tilt
Explain formation of bands
•hot equatorial gas expands and moves towards poles
•polar air flows to equator
•different molecules form clouds at different temperatures (upwelling air cools forms white ammonia clouds)(warm air sinks so depleted of ammonia and we see ammonium hydrosulfide underneath)
•Coriolis effect produces alternating bands of rising and falling air
Describe saturns surface
Like Jupietr, rapid rotation creates fast east-west winds
Clouds deeper in atmosphere so more subdued
Describe neptunes surface
•also banded;high pressure storms like great blue spot
Describe Uranus surface
•very low temps so no energy to drive storms
•clouds very deep in atmosphere no visible bands
•may have seasonal storms
Why is internal heat important for Jovian planets?
Important for weather
How much heat do Jupiter and Saturn radiate in comparison to how much they receive from sun?
Radiate twice as much
Why does Jupiter have a strong magnetic field?
Due to its liquid hydrogen in its envelope and rapid rotation
What does gas escaping from Io create?
Ring of charged particles creating bright aurorae
What rule does Uranus not adhere to?
It’s rotation axis is not perpendicular to the ecliptic
Describe small moons
•<300km
•irregular shape
Describe medium moons
•300-1500km
•no current geological activity
Describe large moons
•>1500km
•ongoing geological activity
Why are small Jovian moons irregular shapes?
Gravity too weak to force them to become spherical
Describe Galilean moons
•4 biggest Jupiter moons
•spherical big enough to form hydrostatic equilibrium
•larger than smallest solar system planet
•ongoing geological activity
What happens if tidal forces bigger than gravitational force holding satellite together?
Satellite will be ripped apart by these tidal forces
When are tidal forces larger?
When planet closer to satellite
What is the Roche limit?
The minimum distance for tidal forces to occur
Which is the closest if Galilean moons to Jupiter?
Io
Describe Io
•about size of our moon
•primarily made up of rock
•most geologically active body in solar system:- no surviving surface craters as more than 400 active volcanoes with plumes of sulfur and sulfur dioxide which climb up to 500km
-tidal heating
-orbits near the Roche limit
Describe Europa
•covered by water ice
•very few impact craters: active geology through water/ice (cyrovolcanism) water acts as lava
•tidal heating (melts sub-surface)
•tidal flexing causes cracking
•magnetic field evidence for salty oceans
What does heat from tidal flexing allow?
Subsurface go remain liquid and potential for subsurface volcanism (hydrothermal vents)
What is the largest moon in the solar system?
Ganymede
Describe Ganymede
•like europa covered in water ice
•dark regions heavily cratered;lighter regions few craters
•upwelling of liquid water which freezes and covers craters
•possible internal heat
Describe Callisto
•Jupiter’s outermost Galilean moon
•heavily cratered ice ball
•light spots recent craters
•no internal heat or tidal heating
What is the only solar system moon with a dense atmosphere?
Titan (90% nitrogen, rest hydrogen compounds)
What did hyugens space probe find on Titan?
Liquid methane on surface and water ice
What are uranuses medium sized moons? Do they have geological activity?
Miranda, Ariel, umbriel, Titania, Oberon and yes
Describe orbit of triton
Orbits at high inclination to neptunes equator and opposite to neptunes rotation (retrograde)
Describe Triton
•probably captured
•surprising amount of geological activity
•has a tenuous atmosphere out of primarily nitrogen
Describe Saturns rings
•made up of particles ranging in size
•frequent collisions (every few hours in densest regions)
•orbits almost perfect circles
•age probably over 100 million years
Can moons inside rings open gaps?
Yes (deflection of nearby objects)
Can moons outside rings open gaps?
Yes (resonances)
What are shepherd moons?
Two moons can produce a very bright narrow ring between them
What is the concensus as to the mechanism of ring formation?
No consensus
Theories of ring formation
- Disruption of large moon deflected j to Roche zone: unlikely as rings seen round all four planets
- Left over from formation of planets: ring particles continually colliding and being ground down and spiral into planet due to sunlight pressure and atmospheric drag
- Ring particles constantly replenished: small moons in equatorial plane can survive tidal forces, small impacts release particles from their surface, large impacts destroy
Why are other Jovian planet rings difficult to observe?
Much darker than saturns
