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Department
Natural Science
Course
NATS 1740
Professor
Randy Hoffman
Semester
Winter

Description
Chapter 7 Earth and the Terrestrial Worlds 7.1 Earth as a planet  Surfaces of the 5 terrestrial planets all looked similar when they were young  All 5 made of rocky material that condensed in the solar nebula  All 5 were impacted on by objects  Mercury  Covered in craters except in areas with volcanoes  Venus  Covered in thick atmosphere with clouds that hide its surface from view  Has volcanoes  Mars  Has the largest volcano and canyon Why is earth geologically active? - Surface is being constantly changed Interior Structure  Core: highest density material consisting of metals like sickle, iron  Mantle: rocky material of moderate density (mostly minerals)  Crust: lowest density rock such as granite and basalt  Lithosphere: outer layer of cool rigid rock Differentiation and Internal Heat  Differentiation: results in layers made of different materials - Earth and the other terrestrial worlds were once hot enough inside for their interiors to melt, allowing material to settle into layers of differing density Internal heat and geological activity  Convection: process which hot material expands and rises while cooler material contracts and falls - Larger planets retain internal heat much longer than smaller ones and this heat drives geological activity The Magnetic Field - Earth’s magnetic field is generated by the motions of molten metal in its liquid outer core  Magnetosphere: protective bubble that surrounds our planet What processes shape the earths surface?  Impact cratering: excavation of bowl shaped impact craters by asteroids or comets crashing into a planet  Volcanism: eruption of molten rock or lava  Tectonics: disruption of a planets surface by internal stresses  Erosion: wearing down or building up of geological features by wind water ice  Virtually all geological features originate from impact cratering, volcanism, etc. Impact cratering - Travel at 40,000 – 250,000 km/h - Like all terrestrial worlds, earth was hit by impacts when it was young but most ancient craters have been erased by other geological processes Volcanism - Earth’s atmosphere and oceans were made from gases released from the interior by volcanic outgassing  Outgassing: water and gasses are trapped beneath the surface, later erupt releasing some of the gas into the atmosphere - Our atmosphere is 77% Nitrogen Tectonics  Plate tectonics: plates that move under, over and around each other - Tectonics and volcanism generally occur together because both require internal heat and therefore depend on a planets size Erosion - Erosion can both break down and build up geological features - Much bigger role on earth than any other planet How does Earths atmosphere affect the planet? - Our atmosphere is 77% nitrogen and 21% oxygen and rest other gasses Surface protection - Ozone absorbs the suns dangerous ultraviolet radiation while xrays are absorbed by atoms and molecules higher up in the atmosphere - Ozone located in stratosphere The greenhouse effect - Our atmosphere traps additional heat making the earth really warm - The greenhouse effect keeps earths surface much warmer than it would be otherwise allows water to stay liquid over most of the surface - Greenhouse effect only occurs when atmosphere contains gasses that can absorb infrared light  Greenhouse gasses: good at absorbing infrared light  H20 CO2 CH4 7.2 The Moon and Mercury: Geologically Dead Was there ever geological activity on the moon or mercury? Geological feathers of the moon  Lunar maria: smooth/dark regions on the moon - Moon is heavily cratered - The moons dark smooth maria were made by floods of molten lava billions of years ago, when the moons interior was heated by radioactive decay - No longer geologically active Geological features of mercury - Lots of impact craters but less crowded together than moons - No longer has volcanic activity - Caloris basin huge impact crater - Mercury seems to have shrunk long ago leaving long steep cliffs 7.3 Mars: A Victim of Planetary Freez
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