Allison Thompson Chapter 7 Notes

chapter 7  earth and terrestrial worlds

mercury
*craters, smooth plains, and cliffs

Venus
*Volcanoes, few craters

Mars
*Some craters, Volcanoes, possibly riverbeds

Moon
*craters and smooth plains

Earth
* volcanoes, craters, mountains, and riverbeds

Why is Earth geologically active?
*Rocky crust, mantle, metal core, rigid lithosphere.
*Core
highest density
*Mantle
Medium density
*Crust
lowest density
Gravity pulls high density material to the center

Lithosphere
A planets outer layer of cool rigid rock
it floats on warmer softer rock beneath it.
strength of rock
*rock stretches when pulled slowly, but breaks when pulled rapidly.

*Convection
hot rock rises and cool rocks fall

sources of internal heat
1.Gravitational potential energy of accreting planetesimal
2. differtatiom
3. radio activity

heating if interior over time
1.Accretion differentiation when planets were young.
2. Radioactivity decay is an important energy source.

Cooling of interior
*Convection transports heat as hot material rises and cool material falls
*conduction transfers heat from hot material to cool material
*Radiation sends energy to space.

Smaller worlds cool off faster and hardens earlier
Mercury and the moon are geologically dead

Heat content depends on volume
Loss if heat through  Radiation depends in surface area
Time to cool depends on surface area divided by volume

Planetary magnetic fields
Moving charged particles create magnetic fields
A planet's interior can create magnetic fields if its core is electrically conducting convecting and rotating.

Earths magnetosphere
earth’s magnetic field protects us from charged particles from the sun.
the charged particles can create an aurorae

How do were know What is inside a planet?
P waves push matter back and forth
P waves go through earths core
S waves shake matter side to side.
Were conclude that earths core must have liquid surface


Why do water and oil separate
A: Water is denser than oil


What processes shaped Earth's surface?
* impacting crater
Impacts  by asteroids or comets
most cratering happening soon after the solar system formed
craters are about 10 times larger if than the item that makes them.
*Volcanism
eruption of molten rock onto surface
happens when molten lava finds its way to the surface
molten rock is called lava after it reaches the surface
out gassing is when Volcanoes release gas from earth’s interior into atmosphere
*Tectonics
Convection of mantle creates stress in the cruat
compression forces make mountain ranges
*Erosion
is a blanket term fir weather driven process that breaks down or transport rock
process that include erosion are glaciers and wind

How does earth atmosphere affect the planet?
erosion
Radiation protection
all x-ray light is absorbed very high in the atmosphere
ultraviolet light is absorbed by ozone
greenhouse effect
certain moluces let sunlight through but trap escaping infrared
any gas that absorbs infrared
mocules with 2 different types of elements
makes sky blue
atmosphere scatters blue light from the sun making it appear to come different directions
sunsets are red because less of red light from the sun.

7.2
Was there ever geological activity on the moon or Mercury?
moon
Some volcanic activity 3billion years ago must have flooded lunar craters.

Mercury
long cliffs indicate that Mercury shrank in nearly history

7.3
What geological features tell us that water once flowed on Mars
50% size earths radius 1/10 earths weight
1.5 au from sun
axis tilts about the same as earth
similar rotation period
co2 atmosphere
little green house
mars is smaller

seasons of Mars
more extreme in southern hemisphere
seasonal winds on Mars can drive huge dust storms

What geological features tells us about water on Mars
conditions of craters indicates surface history
polar caps
Volcanoes as recent as 180 million yrs ago
moat water is frozen underground

Why did Mars change
mores has not had widespread surface water for 3 billion years

7.4!
is Venus geologically active?
cratering on Venus
many Volcanoes
fractured and contorted surface indicates stress
erosion

Why is Venus so hot?
greenhouse effect keeps surfaces 470°C
Venus has very thick carbon dioxide atmosphere
carbon dioxide atmosphere produces an extremely strong greenhouse effect
earth escapes fate because there is water and rocks
reflective clouds keep sulfuric acid
upper atmosphere has fast winds with no explanation
Runaway greenhouse effect
would account Why Venus has little water

7.5
What unique features of earth are important for human life
surface liquid water
atmospheric oxygen
plate tectonics
climate stability

continental motion
can be measured with gps
puzzle like fits of continents
seafloor is recycled through a process known as subduction

plate motions
measure of plates tell us past/future layouts

carbon dioxide cycle
dissolves in rain water
erodes minerals that flow into the ocean
minerals combine with carbon to make rocks on ocean floors
subductuons carry rocks to mantle

How is human activity changing our planet
human made cfc in the atmosphere destroyed ozone
human activity is driving other species to extinction
humans use  fossil fuels produces greenhouse gases

global warming
co2 is rising
an unchecked rise in greenhouse gases will eventually lead to global warming

What makes a planet habitable
distance from the sun
large enough