What are the most importanat (geological) processes involved in the shaping of planetary surfaces?
volcanism- volcanoes and volcanic eruptions
meteor impacts- craters
What are some of the different types and characteristics of impact craters, and how do they relate to the size of the impacting object?
craters form 20 times bigger than the object that caused the crater
1. punch bowl/simple crater- smallest, usually caused by objects less than 1 mile in diameter
2. central-peaked crater- group of mountains in middle of crater, created by objects 1-5 miles wide
3. multi-ringed impact basin- largest, multiple rings spread out from center, at least 5 mile wide impacter
How can one use impact craters to estimate the age of a planetary surface?
crater count- counting amount of craters in an area and dividing that number by the area
What are some of the effects that a meteor impact would have on earth?
produce a crater
blast huge amounts of dust and molten rock into the air
molten rock raining down would raise the surface temp extremely high causing global wildfires
hot fragments and blast would create nitrogen oxides which would combine with water to form nitric acid rain
the toxic combination of heat, acid rain, and blast would be followed by months of darkness and intense cold caused by the dust shroud blotting out the sun
What role does volcanism and erosion play in the shaping of planetary surfaces?
erosion- wears away rock and other surface materials (if the earth had no geological activity to rebuild mountains, the action of rain, flowing water, and waves would have gradually ground down the earth until the entire surface would be under water)
volcanoes- lava flows smooth out the surface
smoothed out areas on moon that are completely devoid of water
largest volcanic feature
largest volcano is solar system
found on Mars
shield volcano (most common)
least violent eruptions
large craters in center (caldera), irregularly shaped unlike impact craters
large crater in center of shield volcano
irregularly shaped unlike impact craters
180 km (110 mile) wide crater found in Yucatan region in Mexico
the region of space surrounding a planet where its magnetic field deflects away the solar wind
the area between a magnetosphere and an ambient medium
the abrupt boundary between a magnetic field and surrounding plasma
formed by pressure from the solar wind on a planet's magnetosphere
Geologically dead planet
no heat left
no volcanic activity
no plate tectonics
Geologically active planet
some heat left, still hot inside
volcanoes, quakes, plate tectonics still occur
Mercury's day and year
solar day- 176 earth days
orbital period (year)- 87.969 earth days
rotation period- 58.646 earth days
spins three times for each two trips it makes around the sun
the day is longer than the year
Why is Mercury probably made mostly of iron?
the iron core is based on its density
although a massive planet's gravity can compress its interior to high density, Mercury is too small for this effect to be significant. therefore its high density indicates an iron-rich interior with only a think rock mantle
giant (mile high) cliff on Mercury and the moon (but not as big)
the planet cooled and shrank, wrinkling, crust collapsed into mantle causing scarps
Why doesn't Mercury have an atmosphere?
its gravitational attraction is too weak to retain any significant amount of gas
its closeness to the sun makes its temp higher which in turn causes any gas molecules there to move so rapidly that they readily escape into space
Why does Mercury probably have a magnetic field?
a magnetic field is generated by circulation of electrically conducting material in a planet's interior
mercury is too small to have a molten core therefore, the outer iron core may be mixed with sulfur which can lower the melting temperature
Why might Venus have such a slow rate of rotation?
Venus had a faster retrograde spin in the distant past and the sun's tidal effects slowed it down to its current rate
What is the dominant geological process affecting Venus' surface?
highland region on Venus
located near Venus' equator
highland region on Venus
studded with volcanic peaks
volcanic peak on the ishtar terra of Venus, including tallest volcano
only male name on Venus
large, crown-like volcanic features on Venus
What is the composition and some of the properties of Venus' atmosphere?
96.5% C, 3.5% N, trace amounts of water vapor and other gases
lightning storms, but no rain
clouds composed of sulfuric acid droplets
clouds permanently cover the planet and are very high and thick (cannot see through them with ordinary telescope)
below clouds, atmosphere is relatively clear and some sunlight penetrates to surface
pressure 90 times that of earth's
>900 degrees F, 500 degrees C
Runaway Greenhouse Effect
greenhouse effect- heat enters the atmosphere, but does not leave
heating has driven the temperature up, and the heating has led to an even stronger greenhouse effect
happened to Venus (Venus' surface is hotter than Mercury's even though it is further from the sun)
Does Venus have a magnetic field?
no. it does not have a dynamo which requires a conducting liquid, rotation, and convection
Venus lacks convection in the core
What sort of tectonics occur within the earth?
convection- circulating movement of a heated liquid or gas
rifting- the mantle stretches and spreads the crust, breaking apart
subduction- one plate is driven back down into the mantle
What are the dominant physical processes that shape the earth's surface?
In what ways is the earth different from the other planets?
atmosphere is 80% N2 and 20% O2
it currently has plate tectonics
What is the composition and some of the properties of earth's atmosphere?
80% N and 20% O
troposphere- dense lowest layer of atmosphere where water vapor circulates, clouds form, and the air is very turbulent
stratosphere- stable layer above troposphere which contains gases such as ozone to shield the earth's surface from most of the short-wavelength radiation from space
inonosphere- where most molecules and atoms have been broken apart into ions
Why does the earth have a powerful magnetic field?
it has a magnetic dynamo process which is generated by electric currents flowing in its molten iron core
What are the dominant two types of surfaces on Mars and where do they occur?
southern cratered highlands
What type of tectonics may occur within Mars, and what are the dominant physical processes that shape/have shaped Mars' surface?
an uplands region spanning the equator of Mars about the size of North America
an enormous rift along the equator of Mars
would span the continental US
What is the composition and some of the properties of Mars' atmosphere?
95% CO2 and 3% N with traces of O and H2O
similar to Venus' but far less dense
-80 to -140 degrees F
clouds made of dry ice and water ice crystals
thinned due to: weak gravity, ablation, dry ice
In what ways has water and ice played a role in Mars' past and how may they play a role now?
Mars may have had a denser and warmer atmosphere in the past, allowing liquid to exist. when Mars lost it's atmosphere cause the planet to plunge into a permanent ice age. gas molecules escaped and water molecules evaportaed. as Mars cooled, the remaining water froze solid and wind buried the ice under protective layers of dust
Does Mars have seasons?
yes. it's axial tilt produces a pattern of seasons similar to earth's, but more extreme because the atmosphere is much less dense
What is Jupiter primarily composed of?
90% H, 10% He
Why is the atmosphere of Jupiter so turbulent?
it has deep circulation (convection currents carry warm gas upward and into space, as it cools, it sinks back down) and rapid rotation
What are some of the different compositional types of clouds that occur in Jupiter's atmosphere?
whitish yellow bands of clouds made of ammonia ice
found on jupiter
dark orangeish brown bands of clouds made of ammonium hydrosulfide
found on jupiter
The great red spot
turbulent storm, twice as big as earth
high pressure system unlike hurricanes and cyclones
found on jupiter
Why does Jupter have such a powerful magnetic field?
convection in the metallic liquid hydrogen combines with the planet's rapid rotation which is driven by a natural dynamo process
Does jupiter have a ring?
narrow "bright" ring (main) with sparse, broad rings (Gossamer Rings)
maintain rings, prevents particles from spreading out and dispersing
How many moons does jupiter have and where did they come from?
they aggregated from planetesimals and gas that collected around the gas giant during formation or were captured after passing by closely to the planet
In what ways is Saturn similar to Jupiter in terms of internal structure, composition, and atmosphere?
96% H and 3% He
cloud composition is ammonia and water
has shepherd moons orbiting amongst rings
oblate spheroid (egg-shaped)
What are the differences between Jupiter and Saturn?
Saturn has less prominent zones and belts
Saturn has more rings
What are the rings of Saturn composed of?
countless small particles made of ice and dust
How many moons does saturn have?
In what ways is Uranus distinct from Jupiter and Saturn?
half the size of Saturn
tipped on side
What is the composition of Uranus' atmosphere and why is it blue-green?