Chapter 8 Flashcards
Earth’s geology: what is plate tectonics?
plate tectonics
the motion of segments or plates of the outer layer of a planet over the underlying mantle
Earth’s geology: what is continental drift?
- The idea of continental drift was inspired by the puzzle-like fit of the continents.
- Mantle material erupts where the seafloor spreads.
Earth’s geology: What caused plate tectonics and continental drift?
thermal convection, where heat from the Earth’s interior causes currents of hot rising magma and cooler sinking magma to flow, moving the plates of the crust along with them.
Earth’s geology: Which kinds of terrestrial worlds cooled off faster after they formed?
• Smaller worlds cool off faster and harden earlier.
Earth’s geology: What is differentiation?
differentiation, the process of sorting the major components of a planet by density.
Earth’s geology: What is the Earth’s core like? What causes the Earth’s magnetic field?
Core: highest density; nickel and iron
A global magnetic field, generated in the core, produces Earth’s magnetosphere, which can trap charged atomic particles.
A world can have a magnetic field if charged particles are moving inside.
Earth’s atmosphere: what is the greenhouse effect and what is a greenhouse gas?
The greenhouse effect is the absorption of infrared radiation near the surface of a planet, for example, by CO2 in its atmosphere.
A greenhouse gas is an atmospheric gas that absorbs and emits thermal infrared radiation.
Earth’s atmosphere: What does a greenhouse gas do to raise the temperature of a planet’s atmosphere?
outgassing, evaporation/sublimation, and impacts by particles
and photons
Earth’s atmosphere: What was the role of the oceans in keeping carbon dioxide out of the atmosphere?
Oceans dissolve atmospheric CO2, enabling carbon to be trapped in rocks.
Venus and Mars: What is Venus generally like? Why is its atmosphere so hot?
• Venus has an extremely thick carbon dioxide atmosphere with a surface pressure 90 times that of Earth; slow rotation results in a very weak Coriolis effect and no weather.
Runaway greenhouse effect made Venus too hot for liquid oceans.
– All carbon dioxide remains in atmosphere, leading to an extreme
greenhouse effect.
Venus and Mars: What are some major features on Mars (giant volcano, deep canyon, polar caps, water in the past). What happened to Mars’s atmosphere and magnetic field?
•Mars has heavily cratered highlands in its southern hemisphere, but younger, lower volcanic plains over much of its northern half.
—Seasonal polar caps are made of dry ice; the northern residual cap is water ice, whereas the southern permanent ice cap is made predominantly of water ice with a covering of carbon dioxide ice.
—exploring ancient lakebeds and places where sedimentary rock has formed, have found evidence for extensive surface water in the past.
Magnetic field may have preserved early Martian
atmosphere.
• Solar wind may have stripped atmosphere after field
decreased because of interior cooling.
