Comparative Planetology involves evaluating the similarities and differences that planets have and is a better way to learn about planets than studying them individually. All terrestrial planets have four stages of development in common. The first stage is differentiation and involves the material of a planet separating according to <1> where the <2> material $phrase. The second stage is known as <3> which was common in the early solar system as there were many planetesimals left over from the period of planet building. The third stage consisted of flooding by lava when the cores heated due to decay of radioactive elements. The final stage is known as slow surface evolution which is still going on today.
We can learn about the core of the Earth through seismology - the study of waves traveling through the Earth. There are two types of waves -- pressure waves and shear waves -- which have very different properties. <4> waves travel more rapidly while <5> waves cannot pass through liquids. Timing the arrival of waves produced by earthquakes at various locations on the Earth allows us to learn about the density of the Earth's interior. We have learned that the Earth has four distinct regions: solid inner core, liquid outer core, mantle, and the crust. The Earth's magnetic field is produced in the <6>. Plate tectonics occurs due to convection currents in the <7>.
The Earth's atmosphere has seen significant evolution since the time of planet formation. $badGas and <8> escaped into space. Methane and Ammonia were broken apart by <9> radiation. Carbon dioxide dissolved in the oceans. The only surviving constituent of the primeval atmosphere is <10>.
The moon is a very different world than the Earth. Since it is much smaller, it lost its heat of formation quickly. It has no atmosphere and the only form of surface evolution is cratering by meteorites. We see two distinct types of terrain on the moon -- highlands and maria. The highlands were formed by large impacts and reflect a much <11> time in the moon's history. The maria are hugh flattened plains of hardened lava responsible for the moon's very low albedo.
@ qu.1.1.algorithm= $num1 = rint(2); $phrase=switch($num1,"rises to the surface","sinks to the core"); $goodChoice = switch($num1,"lighter","heavier"); $badChoice = switch($num1,"heavier","lighter"); $num2 = rint(2); $goodGas = switch($num1,"Hydrogen","Helium"); $badGas = switch($num1,"Helium","Hydrogen"); @ qu.1.1.blank.1=density,weight,composition,metallicity@ qu.1.1.blank.2=$goodChoice,$badChoice@ qu.1.1.blank.3=cratering,flooding,radioactive decay,accretion,condensation@ qu.1.1.blank.4=Pressure,Shear@ qu.1.1.blank.5=shear,pressure@ qu.1.1.blank.6=liquid outer core,solid inner core,mantle,core@ qu.1.1.blank.7=mantle,liquid outer core,solid inner core,core@ qu.1.1.blank.8=$goodGas,Oxygen,Xenon,Argon@ qu.1.1.blank.9=ultraviolet,infrared,microwave,@ qu.1.1.blank.10=nitrogen,oxygen,helium,xenon@ qu.1.1.blank.11=earlier,later@ qu.1.1.grader.1=menu@ qu.1.1.grader.2=menu@ qu.1.1.grader.3=menu@ qu.1.1.grader.4=menu@ qu.1.1.grader.5=menu@ qu.1.1.grader.6=menu@ qu.1.1.grader.7=menu@ qu.1.1.grader.8=menu@ qu.1.1.grader.9=menu@ qu.1.1.grader.10=menu@ qu.1.1.grader.11=menu@ qu.1.2.mode=Blanks@ qu.1.2.name=Comparative Planetology@ qu.1.2.editing=useHTML@ qu.1.2.question=Comparative Planetology involves evaluating the similarities and differences that planets have and is a better way to learn about planets than studying them individually. All terrestrial planets have four stages of development in common. The first stage is differentiation and involves the material of a planet separating according to <1> where the <2> material $phrase. The second stage is known as <3> which was common in the early solar system as there were many planetesimals left over from the period of planet building. The third stage consisted of flooding by lava when the cores heated due to decay of radioactive elements. The final stage is known as slow surface evolution which is still going on today.
We can learn about the core of the Earth through seismology - the study of waves traveling through the Earth. There are two types of waves -- pressure waves and shear waves -- which have very different properties. <4> waves cannot pass through liquids while <5> waves travel more rapidly. Timing the arrival of waves produced by earthquakes at various locations on the Earth allows us to learn about the density of the Earth's interior. We have learned that the Earth has four distinct regions: solid inner core, liquid outer core, mantle, and the crust. Plate tectonics occurs due to convection currents in the <6>. The Earth's magnetic field is produced in the <7>.
The Earth's atmosphere has seen significant evolution since the time of planet formation. $badGas and <8> escaped into space. Carbon dioxide dissolved in the oceans. Ammonia and Methane were broken apart by <9> radiation. The only surviving constituent of the primeval atmosphere is <10>.
The moon is a very different world than the Earth. Since it is much smaller, it lost its heat of formation quickly. It has no atmosphere and the only form of surface evolution is cratering by meteorites. We see two distinct types of terrain on the moon -- highlands and maria. The highlands were formed by large impacts. The maria are hugh flattened plains of hardened lava and reflect a much <11> time in the moon's history.
@ qu.1.2.algorithm= $num1 = rint(2); $phrase=switch($num1,"rises to the surface","sinks to the core"); $goodChoice = switch($num1,"lighter","heavier"); $badChoice = switch($num1,"heavier","lighter"); $num2 = rint(2); $goodGas = switch($num1,"Hydrogen","Helium"); $badGas = switch($num1,"Helium","Hydrogen"); @ qu.1.2.blank.1=density,weight,composition,metallicity@ qu.1.2.blank.2=$goodChoice,$badChoice@ qu.1.2.blank.3=cratering,flooding,radioactive decay,accretion,condensation@ qu.1.2.blank.4=Shear,Pressure@ qu.1.2.blank.5=pressure,shear@ qu.1.2.blank.6=mantle,liquid outer core,solid inner core,core@ qu.1.2.blank.7=liquid outer core,solid inner core,mantle,core@ qu.1.2.blank.8=$goodGas,Oxygen,Xenon,Argon@ qu.1.2.blank.9=ultraviolet,infrared,microwave,@ qu.1.2.blank.10=nitrogen,oxygen,helium,xenon@ qu.1.2.blank.11=later,earlier@ qu.1.2.grader.1=menu@ qu.1.2.grader.2=menu@ qu.1.2.grader.3=menu@ qu.1.2.grader.4=menu@ qu.1.2.grader.5=menu@ qu.1.2.grader.6=menu@ qu.1.2.grader.7=menu@ qu.1.2.grader.8=menu@ qu.1.2.grader.9=menu@ qu.1.2.grader.10=menu@ qu.1.2.grader.11=menu@