Comparing Planets

Io

• closer to Jupiter

• active volcanism (it is the innermost moon)

• tidal heating

• young

• tectonically active

• warmest

• has an eccentric, elliptical orbit

Europa

• tectonic fractures dominate icy surface

• most likely place to find liquid water near surface

• young

• lots of active tectonism

Ganymede

• grooved terrain from tectonic disruptions of cratered surface

• largest satellite

• has its own magnetic field

Callisto

• tectonically inactive

• oldest surface (most cratered)

• greater thickness of ice

• coldest surface

Triton

• small

• rich in nitrogen ice

• has a water ice lithosphere

• has a rocky core

• is in retrograde

• too cold for liquid nitrogen

• neptune’s moon

• its orbit is distinctive because it is in retrograde

• most like Pluto

Uranus

• has a magnetic field that is tilted with respect to the axis of rotation

• thought to have water in its interior

• it has an unexpected orientation

• it is irregular and may be experiencing a reversal

• condensation in a thermal gradient

  • blue color from methane

• planetary rings

• large body impacts

• cooling and satellite expansion

• too small and the internal temperature and pressure are not high enough for metallic hydrogen

• its spin axis is tipped from vertical by over 90 degrees

Neptune

• has a magnetic field that is tilted with respect to the axis of rotation

• thought to have water in its interior

• orbital evolution

• tidal heating

• icy volcanism

• low surface temperatures

• methane ice clouds

Titan

• has an atmosphere rich in nitrogen and methane

• the only satellite known to have a substantial atmosphere

• the biggest moon of Saturn

• has liquids that flow on its surface- hydrosphere!

• the only moon with dunes

Moon

• planetary body that has the oldest surface

• small planet

• impact cratering processes

• geologic time

• volcanic processes

• tectonic processes

rocky surface

• Mercury

• Venus

• Earth

• Mars

Gas until very deep

• Jupiter

• Saturn

• Uranus

• Neptune

• Pluto

Earth

• ideal for the rise of life

• resides in the habitable zone where water is abundant and liquid on the surface

• larger moon stabilizes the tilt, preventing climate extremes and creating tidal zones where life could form

• large planet

  • long history with young surfaces

• plate tectonics

• flow of surface fluids (air and water)

• biosphere

  • effect on atmosphere and tectonics

  • modest temperature!

  • carbon dioxide was removed from atmosphere and life evolved and added oxygen

challenges in finding extrasolar planets

• planets don’t produce light on their own

• they are very far away

• they are lost in the blinding glare of the star

radial velocity

swaying of star due to planet’s gravity

transit

planet crosses in front of star

gravitational lensing

stars bend light around

• the gravity of a massive object bends and distorts the path of light from a distant object behind it

direct imaging

taking actual pictures of planets orbiting other stars

there is a planet around

just bout every star

asteroids

• small planets

• short histories

• condensation in solar nebula

• collisional histories

• planetary differentiation

Mercury

• heat and the strength of the lithosphere

  • warm and weak

  • cooling and contraction

• iron rich planet

  • planet can stay warm enough to maintain a magnetic field

• thrust faults across the surface

• lots of craters

Mars

• larger planet

• has an atmosphere

• eolian processes

• fluvial processes

• tectonism

  • mantle plumes

• volcanism

• lots of lava flows

Venus

• large planet

  • long history with young surfaces (no heavily cratered terrains)

• tectonics

  • mantle plumes

  • counterplumes

• atmosphere evolution

  • greenhouse effect

• hgh surface temperatures and pressures

  • makes it hard for us to explore

Jupiter

• condensation in a temperature gradient

  • so large because ice was stable

• Io, Europa, Ganymede, and Callisto variations

  • composition differences in “mini” accretion disk

  • icy lithosphere

  • tidal heating

Saturn

• planetary rings (are the biggest and brightest here!)

• tidal heating on moons

• icy lithospheres on moons

  • cooling and satellite expansion (which may lead to cracks)

• contains global rifts caused by expansion because of ice

• driven by heat released from the interior

• Hydrogen is the MOST ABUNDANT GAS!

• most similar in composition and internal structure to Jupiter

• has a yellowish tint because of crystals of ammonia ice in the clouds

• magnetic field formed by convection in a shell of metallic hydrogen

Enceladus

• saturn’s small, but still active, moon must be heated by tidal forces

pluto and charon

• condensation in a temperature and mass gradient

• glacial flow

• ice tectonics

• lots of heavy impact craters

• tall mountains are made from WATER ice

• nitrogen and methane are in its atmosphere

comets

• orbital evolution

• condensation in a thermal gradient

• sublimation

planets from smallest to largest

Asteroid, Pluto, Mercury, Mars, Venus, Earth, Neptune, Uranus, Saturn, Jupiter

planets from closest to sun to farthest to sun

mercury, venus, earth, mars, jupiter, saturn, uranus, neptune, pluto, asteroid

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