General composition
1) Jupiter and Saturn consist of hydrogen and helium
2) Uranus and Neptune consist mostly of hydrogen compounds
WHY: less time to attract and accrete for farther from the Sun planets
Density difference
⬆️ m —> ⬆️density (rather than r) —> gravitational compression
Jovian planets’ interiors
Jupiter+Saturn: core (rock/metal/ hydrogen compounds) —> metallic hydrogen —> liquid hydrogen —> gaseous hydrogen —> visible clouds
Uranus+Neptune: core (rock/metal) —> water, methane, ammonia —> gaseous hydrogen —> visible clouds
Weather (clouds, atmosphere)
J+S w layers of clouds (diff chemicals condense at diff t). S’s clouds are deeper in its atmosphere
U+N too cold allowing only some of methane to condense —> methane gas absorbs red light, allowing only blue light to penetrate to reach methane clouds which reemit blue light into space
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Rapid rotation —> winds, storms (the Great Red Spot on Jupiter (high-pressure storm)) + banded appearance (of rising and falling air)
Categories of moons
1) small moons <300 km d
2) medium-sized moons 300-1500 km d
3) large moons > 1500 km d
IO
The most volcanically active world in the solar system
Internal heating despite small size b/c of tidal heating and orbital resonance
Orbits Jupiter on a slightly elliptical plane=> diff distance => diff tidal forces => flexing in diff directions => friction => heating
Europa
Surface of water ice
Subsurface ocean between icy crust and rocky mental
Appear visibly cracked b/c of liquid under the surface
Ganymede and Callisto
Ganymede — the largest moon in the solar system; weak tidal heating; subsurface ocean
Callisto — a heavily cratered ice ball; subsurface ocean; no tidal heating —> unknown internal heating source; unknown dark, powdery substance in the low-lying areas
Titan
Saturn’s moon
Second largest moon in the solar system (after Ganymede)
Very thick atmosphere
Consist mostly of nitrogen
Greenhouse effect
Complex atmospheric chemistry produces carbon compounds - the basis of life
Too cold for liquid water. Instead methane and ammonia rains create rivers flowing —> wet climate but with liquid methane rather than liquid water
Enceladus
The smallest world in the solar system known to be geologically active
WHY: b/c of orbital resonance with another moon
Has a subsurface ocean of liquid water OR liquid ammonia mixture
Triton
Neptune’s moon
Orbits Neptune backwards —> hypothesis that it was captured
Has evidence of relatively recent geological activity —> hypothesis; due to friction when captured
Why do Jovian moons more geologically active than small rocky planets the same size?
1– energy not only from the Sun + internal heating sources (tidal heating <— orbital resonance)
2– diff compounds: ice melts at much lower t than rock and metal
Jovian planets’ rings
- made from countless ice particles ranging in size from
- Saturn’s particles are mostly made of ice; other planets’ (J,U,N) - icy particles
- all Jovian planets have rings
- each particle orbits independently => rings are like myriads tiny moons
- particles collide frequently but gently as they move in the same direction +- at the same speed
- rings have many rings, gaps, ripples
↪️ formed by some particles bunching up at some orbital distances and being forced out at others
↪️ happens when gravity nudges (подталкивает) the orbit in some particular way
↪️ source: -> small moons within the gaps in the rings
-> larger, more distant moons - rings particals are const recycled/ replaced by new ones
Replacement of ring particles
Particles cannot last for billions of years so the rings we see today must be made of particles created recently
|__ new particles must be continuously supplied to replace those that are destroyed
|__ the most likely source — small “moonlets” ==» new particles are released by impacts of small moons within the rings
