Download File

Chapter 3 Lesson 3.2
The Inner Planets
The Inner Planets
Terrestrial planets(w.w) Mercury, Venus,
Earth, Mars
• All have rocky crusts, & dense mantles &
cores
• Their insides, surfaces, & atmospheres
formed in similar ways & follow similar
patterns
The Inner Planets
Processes & Surface Features
• All inner planets have layers with rocky surfaces.
– Heaviest materials were metals which sank to center & formed a
core.
– Lighter rock formed mantle around core.
– Lightest rock formed crust along surface.
• 4 Processes shaped each planet’s rocky crust:
1. Tectonics(w.w). Process of change in crust due to motion of hot
material underneath. Mountains, valleys, etc form as plates
move under Earth’s crust. Earth only 1 w/ plates that move
•
DEMO- Blocks, wet paper towel, newspaper.
2. Volcanism(w.w) when molten rock moves from planet’s hot
interior to surface. Earth, Venus, Mars
3. Weathering & Erosion- wind, water, temp change
4. Impact Cratering- explosions caused by impacts of objects on
planet’s surface.
Atmospheres
• Mainly formed from gases that pour out of volcanoes
(if planet’s gravity is strong enough, it pulls the gases in
& keeps them near surface)
• Venus, Earth, Mars had gravity strong enough to hold
heavy gases such as CO2. (Mars/Venus are mostly CO2)
• Atmosphere moves from warmer places to cooler
places. Keeps planet surface warmer & stable between
day/night.
• After Earth formed, CO2 kept it warm enough that
water remained liquid. This changed gases of
atmosphere & then living organisms caused even more
change. Now our atmosphere is mostly Nitrogen & O2
About the Other Inner Planets
• Mercury
– Processes at work on Mercury
• Tectonics- long high cliffs
• Volcanism- long ago parts of surface was covered with lava has now
hardened (like maria on Moon)
• Weathering & Erosion- impacts, gravity moves broken rock downhill
• Impact Cratering- Like our Moon b/c it has MANY craters
• Seems to have oldest, least-changing surface
• Has longest cycle of day & night of the inner planets = 3
months daylight/3 months darkness
• No atmosphere.
• Daytime temps- about 800 degrees F
• Nighttime temps- about -280 degrees F
About the Other Inner Planets
• Venus
– Processes at work on Venus
• Tectonics, Volcanism: still shaping surface. Cracks/cliffs &
Volcanoes & lava plains are found all over surface
• Weathering & Erosion- too hot for water & not much wind
• Impact Cratering- atmosphere protects from most
•
•
•
•
Takes about 8 months to rotate once on axis
Only a little smaller than Earth.
2 months daylight/2 months darkness
Atmosphere is very dense. Air pressure 90XEarth
• Mostly CO2
• Temperature- about 870 degrees F at all times in all places
About the Other Inner Planets
• Mars
– Processes at work on Mars
• Tectonics- has valleys & raised areas (1 valley long enough to
stretch across the U.S.!
• Volcanism- several large volcanoes. N. Hemisphere- smooth
plains of cooled lava
• Weathering & Erosion- fast winds, dust storms
• Impact Cratering- S. Hemisphere- many round craters
• Smaller than Earth. Has 2 tiny moons.
• 2 months daylight/2 months darkness
• Atmosphere is very thin. Only about 1% Earth’s air pressure.
•
•
•
•
•
Mostly CO2 . Polar caps are frozen CO2 (dry ice)
Orange color of surface from iron & oxygen (rust!)
Daytime temps- about 60 degrees F
Nighttime temps- about -130 degrees F
No liquid water, but still water frozen in ground and in 1 polar
ice cap
Lesson 3.2 Review Q’s 14 points
1. What are the 4 types of processes that shape planets’ surfaces?
For each one give an example of a feature that can come from
the process. (8 points)
2. How can an atmosphere affect the temperature of a planet’s
surface?
3. Which inner planet has the oldest least-changing surface?
4. What does “tectonics” mean? Which inner planet sees this the
most?