UT Arlington ASTR 1345 - Exam 3 Study Guide (6 pages)

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Exam 3 Study Guide

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Exam 3 Study Guide


Goes through lectures 18-22

Study Guide
University of Texas at Arlington
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ASTR 1345 1nd Edition Exam 3 Study Guide Lectures 18 22 Lecture 18 November 6 Origin of the Solar System What do we know about our Earth The Earth is made of 74 Helium 25 Helium and 1 consisting of heavier elements A cloud gas collapses if it has a low temperature so that the outward thermal pressure is small or high density so gravitational pressure causes the cloud to collapse inwards It also collapses if the disk is rotating The rotation of the Earth would be faster without the Moon Earth developed a permanent atmosphere because speeds imparted to the gases of the second atmosphere by sunlight were not high enough to enable them to leave Earth s gravitational bonds Helium and Hydrogen through geographical change formed volcanoes that created CO2 and those 3 then created toxic water and very primitive bacteria Then the CO2 was converted to oxygen by early plant life How do terrestrial planets and gas giants differ Terrestrial planets are mostly solid have a lower mass slower rotation higher density no rings and fewer moons Gas giants are mostly fluid have a higher mass fast rotation lower density rings and many moons What is the troposphere The troposphere is the lowest level of Earth s atmosphere Which is where all of Earth s weather occurs 75 of the mass of the atmosphere lies in this layer Temperature drops from an average 290K at ground level to 218K at 11 km Convection causes the weather It causes hotter air near the ground to rise and cooler denser air to fall What is the stratosphere The stratosphere is the 2nd layer in Earth s atmosphere in the realm of the ozone layer Temperature increases because of the ozone layer What is the mesosphere Mesosphere is the 3rd layer above the stratosphere Temperature drops to a minimum of 200K What is the ionosphere The ionosphere or thermosphere is the 4th layer above which the Sun s ultraviolet radiation heats and ionizes atoms producing charged particles that reflect radio waves Lecture 19 November 11 Earth and the Moon What is Earth s core made of The Earth s core is of iron and nickel surrounded by less dense mantle and a thin outermost crust The inner core is solid because of very high pressure while the outer core is liquid What is the mantle The mantle consists largely of minerals rich in iron calcium and magnesium It s made of hot plastic like rock that flows slowly to Earth s surface The mantle breaks the crust in a process known as rifting What is the crust The crust is Earth s outermost layer composed of relatively low density rock Define plate tectonics Plate tectonics is the motion of large plates of Earth s surface caused by convective motions in the underlying mantle Define continental drift Continental drift is the gradual movement of continents over the surface of Earth due to plate tectonics Define seafloor spreading Seafloor spreading is when magma upwells along rifts in the ocean floor causing adjacent segments of Earth s crust to separate What is the Moon s surface The Moon s surface is powdered rock built up over billions of years Although it s not moist it sticks together like wet sand What covers the Moon Mare covers 17 of the moon It is the large relatively crater free plain on the moon and was caused by magma from the Earth s core Define rilles Rilles are winding cracks in the surface caused by the collapse of solidified lava tube What is the Moon s temperature Night time surface temp inside the coldest craters in the northern polar region have been measured as low as 26K During the day temps At the equator can reach 400K which indicates that the moon has one of the most extreme thermal environments How does the Moon affect Earth s tides The water on the part of Earth s surface closest to the Moon experiences stronger gravitational attraction to the moon than the body of Earth What is high tide Water is pulled away from the surface by the Moon which is high tide What is tidal shift The difference in water heights between high and low tide is known as tidal shift What are spring tides Spring tides are the largest tidal shifts and occur when the Sun and Moon pull in the same direction This occurs when all three are in a straight line What are neap tides The smallest tides are neap tides and occur when the Sun and Moon pull in opposite directions Lecture 20 November 13 Mercury Venus Mars What do we know about Mercury Mercury is 20 the size of the Earth and has extreme variations in temperature Mercury has no seasons and there are traces of an atmosphere Mercury is filled with subtle blue and red areas and wrinkle like ridges are an indication that Mercury is shrinking It has active volcanoes and a magnetic field What is the Caloris Basin Caloris Basin is found on Mercury and it is a crater of about 800 miles in diameter It was probably formed by a major impact that occurred early on and shock waves from the impact produced a hilly landscape on the opposite side of the planet What do we know about Venus Venus is about the same size as Earth and has a runaway greenhouse effect caused by its dense toxic atmosphere which is hot enough to melt iron Venus has no magnetic field and only the Moon outshines Venus because of its proximity There are a lot of lava plains and the surface temperature is 750K at all times and latitudes What do we know about Mars Mars is half the size of Earth and contains the highest mountain and the deepest and longest valley Because of its smaller size the interior f Mars cooled faster than Earth s so surface activity has ceased Mars sky is red due to fine iron oxide rust There are multiple indications that Mars once had water Lecture 21 November 18 Space Missions and Jupiter What are Mars moons Mars has 2 small moons named Phobos and Deimos discovered in 1877 by Asaph Hall Phobos is potato shaped and its period of 5 hours means it orbits faster than Mars rotates so it moves west to east across the sky It is now believed that this moon is more like a pile of rubble Deimos moves from east to west across the sky in about 3 Earth days What happened with Voyager 1 and Voyager 2 Voyager 1 and 2 each reached Jupiter in 1979 Saturn gave Voyager 1 a gravitational slingshot out of the Solar System Voyager 2 used Saturn s gravity to propel it closer to Neptune 1986 and Uranus 1989 In 2008 after 31 years of travel both Voyagers crossed different parts of the solar system boundary known as the termination shock 90 AU from the Sun What was the Galileo mission Galileo made 3 passes through the inner

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