Chapter 7 astronomy
What is the carbon dioxide cycle, and why is it so crucial to life on earth?
- The constant cycling of carbon through the living and non-living world. - Carbon is the fundamental basis of all living things. We can't live without it, so if there are uneven amounts of carbon in the atmosphere then there will be disastrous consequences like global warming.
Explain why liquid water is not stable on mars today, but why we nonetheless think it flowed there in the distant past.
- a.) Because Mars is so cold, so water would immediately freeze into ice; air pressure is so low that liquid water would quickly evaporate. - b.)It is believed that Mars had different surface conditions in the past; warmer temperatures and greater air pressure
Briefly summarize the evidence linking human activity to global warming. What are its potential consequences?
-Burning of fossil fuels- increasing the atmospheric concentration of carbon dioxide and other greenhouse gases which leafs to global warming. -Polar regions melting- species suffer as more salt water mixes with fresh water -gulf is warmer- more hurricanes more severe blizzards -fresh water ay alter ocean currents- gulf stream -sea level rising- water expands when it is warmer, floods in low lands
Define the four major geological processes, giving examples of features on Earth shaped by by each process.
1.Impact cratering - bowl shaped craters. Scar impacts on Mars and the Moon - 2.Volcanism - eruption of molten rock and lava from planets interior onto surface. Creates volcanic plains, shield volcanoes and stratovolcanoes. - 3.Tectonics - disruption of planets surface by internal stresses. Appalachian Mountains, Guinevere Plains, Ceranus Valleys, Rio Grande - 4. Erosion - wearing down or building up of the geological features by wind, water, ice and other planetary weather. Shaping of valleys by glaciers, carving of canyons by rivers.
Describe the leading hypothesis for how mars lost much of its atmosphere some 3 billion years ago, and identify the role played by mars' size.
After mars lost it's magnetic field solar wind particles stripped away the atmosphere. The size of the planet it important for explaining why the magnetic field was lost. The magnetic field would have been sustained by the movement of molten metal in the core. However, a small planet like Mars cools more quickly, so the metal stops moving and the magnetic field weakens. losing the carbon dioxide gas weakened greenhouse affect contributing to the freezing of the planet atmospheric gases are vulnerable to solar wind particles stripping gases out of the martian atmosphere into space
why did the terrestrial worlds undergo differentation? why have larger worlds retained more internal heat than smaller ones?
Mercury, venus, earth, mars. Once they'd formed, quickly melted as result of large scale impacts and radioactive heating. Heavier materials sink, lighter to surface when molten.also with convection which is hot material expanding and cooling as it rises upward Larger planets have more insulation.
What is outgassing, and how did it lead to the existence of Earths atmosphere and oceans?
Outgassing - the release of pressure expelling trapped gasses from molten rock. most gas is water which goes to oceans other 77 percent goes to asmosphere
Describe the key ways in which the atmosphere affects Earth. What is greenhouse effect, and how does it work?
Surface protection - protects us from Sun's radiation (ionizing photons) Greenhouse effect - atmosphere traps additional heat (some light absorbed, some reflected. Reflected in form of infrared light. GE occurs when the atmosphere temporarily traps some of the infrared light that the ground emits, slowing its return to space.) Occurs only when the atmosphere contains gases that can absorb infrared light (greenhouse gases: H2O, CO2, methane (CH4).
Why does earth have a global magnetic field? What is the magnetosphere?
The leading theory is that it is caused by the churning liquid of the earth's outer core. protects earth from solar wind This may explain why the earth's magnetic pole has shifted several times throughout the earth's history. - Magnetosphere - the region surrounding the earth or another astronomical body in which its magnetic field is the predominant effective magnetic field. also internal heat causes liquid metal to rise and fall while earths rotation twists and distorts the convection pattern
roles of planetary size and distance from the sun
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How do crater counts tell us the age of a surface? Explain why the moon has so many more craters than earth.
- Because most of the Earth's impact craters have been covered overtime by geological processes such as volcanic eruptions and erosion. - More craters indicate older surface. A geological surface looks about the same as it did billions of years ago.
Describe four ways in which earth is unique among the terrestrial worlds, and how each is important to life.
1. Earth retains most of its outgassed water- temps were low enough for water vapor to condense into rain and form oceans 2. Earth has very little carbon dioxide- oceans explain why there is little CO2 because most CO2 outgassed by volcanism on earth dissolved into the oceans 3. Composed primarily of nitrogen and oxygen- nitrogen is the 3rd most common gas released by outgassing; oxygen would disappear from our atmosphere if not continuously resupplied/ LIFE, plants, photosynthesis 3stronomy 101 Wednesday, November 5, 2014 4. Has an ultra violet absorbing stratosphere- life and oxygen, chemical reactions form some of the O2 molecules into O3(ozone), absorbs solar ultraviolet energy because it is more weakly bound surface liquid water more simply surface liquid water atmospheric oxygen plate tectonics climate stability
Describe the conveyor-like action of plate tectonics, and how it changes the arrangement of the continents with time
12 plates make up the mantle - mantle material erupts onto the ocean floor, pushing apart the existing seafloor on either side. *mantle convection - New seafloor crust tells us that the continents have gradually built up over time
Describe the basic geology of venus. Why is it surprising that venus lacks plate tectonics? What might explain this lack?
Similar to Earth (occasional impact craters, volcanoes, and a lithosphere that has been contorted by tectonic forces). Unique features (large, circular coronae (Latin for "crowns") that were probably made by hot, rising plumes of mantle rock. These plumes probably also forced lava to the surface, explaining the volcanoes found near coronae.) Plate tectonics re-sculpts the surface gradually, so that different regions have different ages. On Venus, the relatively few impact craters are distributed fairly uniformly over the entire planet, suggesting that the surface is about the same age everywhere. Apparently, the entire surface of Venus was somehow "repaved" at that time. Most scientists suspect that Venus's lithosphere resists fracturing into plates because it is thicker and stronger than Earth's. 5 percent smaller than earth in radius and overall composition is the same but venus surface is a hot house
What do we mean by a runaway greenhouse effect? Explain why this process occurred on venus but not on earth.
Venus is closer to the sun. Hotter temp = more evaporation = hotter atmosphere = hotter temp = more evaporation, etc... UV rays would tear away hydrogen atoms, leaving Venus as we know it.
describe the core-mantle crust structures of the terrestrial worlds. what is lithosphere and what s differentation?
a. Core- the highest density material, consisting primarily of metals such as nickel and iron, resides in the central core. b. Mantle- rocky material of moderate density mostly minerals that contain silicon, oxygen, and other elements- forms the thick mantle that surrounds the core. c. Crust- the lowest density rock, such as granite and basalt (a common form of volcanic rock), forms the thin crust, essentially representing the world's outer skin. d. Differentiation- the process by which gravity separates materials according to density, with high-density materials sinking and low-density materials rising. e. Lithosphere- the relatively rigid outer layer of a planet; generally encompasses the crust and the uppermost portion of the mantle.
Briefly summarize the geological histories of the moon and mercury. How did the lunar maria form? How are mercury's great cliffs thought to have formed?
a.) Due to the Moons small size, it may have lost its internal heat leaving it without any volcanoes or tectonics to cover the craters. The small size contributes to the lack of atmospheres and erosion. The weak gravity inhibits the Moon form holding gas for long periods, and without ongoing volcanoes, it lacks outgassing needed to replenish gas lost in the past. - b.) Lunar maria- smooth dark regions on the Moon's surface (look like oceans when see form afar); Due to the heat released by the decay of radioactive elements in the Moon's interiror, lava floods came. Molten rock then welled up through the cracks of the moon's lithosphere, flooding the largest impact craters with lava. - c.) Cliffs are thought to have formed when tectonic forces compressed the crust causing the surface to crumple.
