Amber Reed Notes

Chapter 7:

-Mercury as craters,smooth plains and cliffs

-Venus has volcanoes and few craters

-Mars has some craters, volcanoes and possible riverbeds
-biggest volcano in solar system is on Mars

-Moon has craters and smooth plains

-Earth has volcanoes,raters,mountains and riverbeds

Chapter 7.1

Why is Earth geologically active?
-its because of the size and mass
-Core: highest density <nickel and iron>
-Mantle: Moderate density <silicon,oxygen and etc>
-Crust:Lowest density<granite basalt and etc>
-after applying what we learned about Earth interiors to other planets tells us what their interiors are probably like 

Differentiation: 
-Gravity pulls high density material to center
-Lower density material rises to surface
-material ends up separating by density

Lithosphere:
- a planets outer layer of cool,rigid rock 
-it floats on the warmer ,softer rock that lies beneath

Strength of Rock:
-rock stretches when pulled slowly but breaks when pulled rapidly
-the gravity of large world pulls slowly on its rocky content,shaping the world into a sphere

Heat Drives Geological Activity:
convection: 
-hot rocks rises,cool rock falls
-one convection cycle takes 100 million years on Earth 

Sources of internal heat:
-gravitational potential energy of accreting planetesimals
-differentiation 
-radioactivity

Heating of Interior over time:
-accretion and differentiation when planets were young
-radioactive decay is most important heat source today 

Cooling Interior:
-Convection transports heat as hot material rises and cool materials falls
-Conduction transfers heat for hot materiel to cool material
-Radiation sends energy into space

Role of size:
-smaller worlds cool off faster and harden earlier
-the moon and mercury are now geologically "dead"

Surface area-to-volume ratio
-eat content depends on volume
-loss of heat through radiation depends on surface area
-time to cool depends on surface area divded by volume




Planetary magnetic fields:
-moving charged particle create magnetic fields
-a planets interior van creat magnetic fields if its core is electrically conducting,convecting and rotating

Earth's magnetosphere:
-Earth's magnetic field protects us from charged particles from Sun
-the charged particles can create aurorae ("Northern lights")

How do we know whats inside a planet??
-P waves push matter back and forth
-S waves shake matter side to side
-P waves go through Earth's core, while S waves can not
- we conclude that Earth's core must have a liquid outer layer


What processes shape Earth's surface?
Geological Processes:
-Impact cratering
-impacts by asteroids
-Volcanism
-eruption of  molten rock onto surface
-tectonics
-disruption of a planets surface by internal stresses
-erosion
-surface changes made by wind,water or ice

Impact cratering:
-most cratering happened soon after the solar system formed
-craters are about 10 times wider than the objects that made them
-small craters greatly outnumber large ones

Volcanism:
-volcanism happens when molten rock (magma) finds a path through lithosphere to the surface
-molten rock is called lava after it reaches the surface 

Outgassing:
-volcanism also releases gases from Earth's interior into the atmosphere

Tectonics:
-convection of the mantle creates stresses n the crust called tectonic forces
-compression forces make mountain ranges
-a valley can form where the crust is pulled

Erosion:
-is a blanket term for weather-driven processes that breakdown or transport rock
-processes that cause erosion include:
-glaciers
-rivers
-wind


How does Earth's atmosphere affect the planet?

-erosion
-radiation protection
-greenhouse effect
-makes the sky blue

Radiation Protection:
-all X-ray light is absorbed very high in the atmosphere
-ultraviolet light is absorbed by ozone 

Greenhouse effect:
-without which the surface temperature would be below freezing

greenhouse gas:
-any gas that absorbs infrared
-green house gas -molecules with two different elements
-not a green house gas:molecules with one or two atoms of the same element

why is sky blue.?
- atmosphere scatters blue light from the sun making i appear to come from different directions
-sunsets are red because less of the red light form the sun is scattered

7.2

Mercury and the moon: geologically dead

Was there ever geological activity on the moon or mercury?
-some volcanic activity 3 billion years ago must have flooded lunar craters,creating lunar maria
- mercury has mixture of heavy cratered and smooth regions
water flowed once on Mars
-long cliffs indicate mercury shrank early in its history 

7.3
What Geological features tell us that water once flowed on Mars?

-dry  ancient river beds,eroded craters and chemical analysis of martian rocks all showed
-3 millions years ago rainfall seemed to end
-ice water underground and in its polar caps and could have possibly pockets of underground liquid water

Mars vs Earth:
50% size of Earth, and 1./5 mass of Earth
-similar rotation period
-this CO2 atmosphere:little greenhouse
-Mars is smaller

-seasons in mars are more extreme in the southern hemisphere because of its elliptical orbit
-seasonal winds on Mars can drive huge dust storms

Why did Mars change?
-atmosphere once was thicker with a stronger greenhouse effect, so change must have occurred due to loss of atmosphere gas
-gas stripped away by solar wind, after Mars lost its magnetic field and protective magnetosphere.
-also lost water because of solar Ultraviolet light split water molecules apart an the hydrogen escaped to space

Venus: A hothouse world:

Is Venus geologically active?
-it is active today
-surface shows evidence of major volcanic or tectonic activity in past billion years
-retains the similar amount of internal heat as earth does 
-lack of erosion and lack of plate tectonics
-impact craters
mist of earth;s major geological features can be attributed to plat tectonics, which is gradually remakes earth's surface
-the entire surface seems o have been repaved 750 million years ago

Why is Venus so hot?
-thick carbon dioxide atmosphere, which creates strong greenhouse effect (keeps it surface temp 470 degrees)
-the distance from the sun makes the thick atmosphere for Venus
-reflective clouds contain droplets of sulfuric acid
-the upper atmosphere has winds that remain unexplained 
-the runaway greenhouse effect would account for why Venus has so little water

Earth's as a living planet:

What is unique features of earth are important for life?
- surface liquid water, made possible by Earth's moderate temp
-atmospheric oxygen, a product of photosynthetic life
-plate tectonics,driven by internal heat 
-climate stability, result of Carbon Dioxide Cycle, which requires plate tectonics
- seafloor is recycled thorough  process of subduction


How is human activity changing our planet?
-the global temp has risen about 0.8 Celsius over past hundred years
-larger rise of CO2 concentration, as a result of fossil fuel is burning and other human activity
-current CO2 concentration is higher than at any time in past million years this is because of global warming
-humans are driving other species to extinction

what makes a planet habitable?

-large size
-distance from sun
-internal heat that allowed volcanic outgassing to lead to our oceans and atmosphere
-also drives the plate tectonics that help regulate climate through carbon dioxide cycle
-optimal distance from sun for liquid water existence





Amber Reed