Copyright 2010 Pearson Education, Inc. Lecture Outline Chapter 5 Earth and Its Moon Copyright 2010 Pearson Education, Inc. An amazing fact We are here, after 13.7 billion years, as the first people able to look at the cosmos and contemplate and reflect and understand our place in it. We are made of stuff from the universe, gas and dust and ice, that assembled in an understandable way, and is now able to think. We are the universe looking at itself. Copyright 2010 Pearson Education, Inc. Chapter 5 Earth and Its Moon Start with what we know best The only two bodies in the universe that humans have touched! Alien abductions not included. Copyright 2010 Pearson Education, Inc. Why study the earth? Arent we interested in things beyond earth? 1.Start with what we know, then go where we know less 2.Comparative anatomy 3.Compare and contrast 4.Where have we been? 5.Where might we go? Copyright 2010 Pearson Education, Inc. Units of Chapter 5 Earth and the Moon in Bulk The Tides Atmospheres Interiors Surface Activity on Earth The Surface of the Moon Magnetospheres History of the EarthMoon System Summary of Chapter 5 Copyright 2010 Pearson Education, Inc. First, lets explore Look at Moons of Jupiter Lab in folder Understand how data from a telescope can tell us about moons And can even tell us about mass of the planet P:\Rod on P\school files\physics\Astronomy\moons of jupiter lab from jim lund\Moons of Jupiter lab.pptxP:\Rod on P\school files\physics\Astronomy\moons of jupiter lab from jim lund\Moons of Jupiter lab.pptx P:\Rod on P\school files\physics\Astronomy\moons of jupiter lab from jim lund\Moons of Jupiter Lab 2 up.pdfP:\Rod on P\school files\physics\Astronomy\moons of jupiter lab from jim lund\Moons of Jupiter Lab 2 up.pdf Copyright 2010 Pearson Education, Inc. 5.1 Earth and the Moon in Bulk Density of liquid water = 1000kg/m 3 Density of iron: 7.9Density of granite: 2.8 Copyright 2010 Pearson Education, Inc. Tides are due to gravitational force on Earth from Moon force on near side of Earth is greater than force on far side. Water can flow freely in response. 5.2 The Tides Can we see the swing in solar system simulator? Copyright 2010 Pearson Education, Inc. The Sun has less effect, but it does modify the lunar tides. 5.2 The Tides Have you heard of high-high and low-high etc? Copyright 2010 Pearson Education, Inc.Nova-Scotia/tides/latest Copyright 2010 Pearson Education, Inc. Tides tend to exert a drag force on Earth, slowing its rotation. This will continue until Earth rotates synchronously with the Moon, so that the same side of Earth always points toward the Moon. 5.2 The Tides Copyright 2010 Pearson Education, Inc. 5.2 The Tides This has already happened with the Moon, whose near side is always toward Earth. Copyright 2010 Pearson Education, Inc. Tidal deformation and tidal forces happen for every orbiting body The forces deform the body They take energy They make heat They change the rotation of the body Copyright 2010 Pearson Education, Inc. Quiz for friday For each phase, name it and describe what time of night youd see it (early evening, all night, or before sunrise) Copyright 2010 Pearson Education, Inc. Atmosphere Copyright 2010 Pearson Education, Inc. Influence of atmospheres on a planet or a moon 1.Erosion 2.Protection from solar radiation and ions 3.Temperature 4.Chemistry 5.Life 6.Others?____albedo, asthetics______ Copyright 2010 Pearson Education, Inc. The blue curve shows the temperature at each altitude. Troposphere is where convection takes place responsible for weather. 5.3 Atmospheres, major influence on a planet Copyright 2010 Pearson Education, Inc. Convection depends on warming of ground by the Sun. 5.3 Atmospheres Copyright 2010 Pearson Education, Inc. Ionosphere is ionized by solar radiation, and is good conductor. Reflects radio waves in the AM range, but transparent to FM and TV. Ozone layer is located in the Stratosphere; absorbs ultraviolet radiation. 5.3 Atmospheres Copyright 2010 Pearson Education, Inc. Chlorofluorocarbons (CFCs) have been damaging the ozone layer, resulting in ozone hole. Discovery 5-1: Earths Growing Ozone Hole Copyright 2010 Pearson Education, Inc. Surface heating: Sunlight that is not reflected is absorbed by Earths surface, warming it. Surface re-radiates as infrared thermal radiation. Atmosphere absorbs some infrared, causing further heating. 5.3 Atmospheres Copyright 2010 Pearson Education, Inc. This is known as the greenhouse effect. We like it, otherwise the water would all be frozen! 5.3 Atmospheres The atmosphere is transparent to visible light. Visible hits the ground, is absorbed, and warms the ground. Energy radiates away from the ground in the infrared. But the atmosphere is only partially transparent to infrared. So heat is trapped in the atmosphere, and warms it. Why is the balance changing? Copyright 2010 Pearson Education, Inc. Dec 5: Discovery 5-2: The Greenhouse Effect and Global Warming There is scientific agreement that Earth is getting warmer. The cause of this warming is a subject of intense debate; it is related to the corresponding increase in atmospheric carbon dioxide. Copyright 2010 Pearson Education, Inc. Moons atmosphere Where is it? So what is different about the moon? Wide night-day temperature range: below freezing to above boiling No erosion No kite flying So why is water ice under the moons surface at the poles? Copyright 2010 Pearson Education, Inc. Solve at your table 1. In what ways are atmospheres change agents to the planets surface? stabilizing agents for the planet? 2. Identify and describe the 3 effects that give rise to tides at the coast. Copyright 2010 Pearson Education, Inc. To be in my class: 1.Have your text open 2.Have your notebook open 3.Have a pen in your hand 4.Write some notes 5.Ask at least one question 6.If you dont care, act as if you care Copyright 2010 Pearson Education, Inc. Interiors of the earth and moon Copyright 2010 Pearson Education, Inc. Seismic waves: our only (?) tool to probe into the interior (tapping on the wall of earth) Wave speed depends on density of material. Name 1 other way we learn about interiors. It comes up to the surface: volcano, sea vents 5.4 Interiors, the structure of the earth or moon Copyright 2010 Pearson Education, Inc. 5.4 Interiors The pressure wave is a longitudinal wave, whereas the shear wave is a transverse wave. A shear wave cannot propagate within a liquid. Copyright 2010 Pearson Education, Inc. Can use pattern of reflections during earthquakes to deduce interior structure of Earth. 5.4 Interiors How do they measure these waves? Copyright 2010 Pearson Education, Inc. The model that best fits the earthquake and magnetic and geophysics data 5.4 Interiors Copyright 2010 Pearson Education, Inc. Mantle is much less dense than core. Mantle is rocky and plastic; core is metallic, consisting of iron and nickel. Outer core is liquid; inner core is solid, due to pressure. Volcanic lava comes from mantle, allows analysis of composition. 5.4 Interiors Copyright 2010 Pearson Education, Inc. The moons interior is like the earths Where did the moon come from? The moon has earthquakes, or moonquakes, or quakes. Copyright 2010 Pearson Education, Inc. Surface and surface activity Copyright 2010 Pearson Education, Inc. Continental drift: Earths entire surface is covered with crustal plates, which can move independently. At plate boundaries, earthquakes and volcanoes can occur. 5.5 Surface Activity on Earth Copyright 2010 Pearson Education, Inc. Plates moving away from each other create rifts. 5.5 Surface Activity on Earth If we follow the continental drift backward, the continents merge into one, called Pangaea. Land of enchantment Copyright 2010 Pearson Education, Inc. 5.5 Surface Activity on the Moon Outer crust is too thick, mantle is too solid. So where do moonquakes come from? none Tidal forces, morning heating of cold crust, meteorites, and slumping of younger crater walls Copyright 2010 Pearson Education, Inc. The Moon has large dark flat areas, due to lava flow, called maria (early observers thought they were oceans). 6 dec: 5.6 The Surface of the Moon Copyright 2010 Pearson Education, Inc. The far side of the Moon has few maria. 5.6 The Surface of the Moon Copyright 2010 Pearson Education, Inc. Crater formation: Meteoroid strikes the Moon, ejecting material; explosion ejects more material, leaving a crater. 5.6 The Surface of the Moon Copyright 2010 Pearson Education, Inc. Craters are typically about 10 times as wide as the meteoroid creating them, and twice as deep. Rock is pulverized to a much greater depth. Most lunar craters date to at least 3.9 billion years ago; much less bombardment since then. 5.6 The Surface of the Moon Copyright 2010 Pearson Education, Inc. Very large and very small lunar craters 5.6 The Surface of the Moon Copyright 2010 Pearson Education, Inc. 5.6 The Surface of the Moon Regolith: Thick layer of dust left by meteorite impacts The Moon is still being bombarded, especially by very small micrometeoroids; softens features. Do we have earthquake data of the moon? Copyright 2010 Pearson Education, Inc. The magnetosphere Copyright 2010 Pearson Education, Inc. 5.7 Magnetospheres The magnetosphere is the region around Earth where charged particles from the solar wind are trapped. Copyright 2010 Pearson Education, Inc. 5.7 Magnetospheres These charged particles are trapped in areas called the Van Allen belts, where they spiral around the magnetic field lines. Copyright 2010 Pearson Education, Inc. 5.7 Magnetospheres Near the poles, the Van Allen belts intersect the atmosphere. The charged particles can escape; when they do, they create glowing light called an aurora. Copyright 2010 Pearson Education, Inc. Northern lights from ISS:And from the ground Copyright 2010 Pearson Education, Inc. How to explain with sketch Copyright 2010 Pearson Education, Inc. History of earth-moon Copyright 2010 Pearson Education, Inc. Current theory of the Moons origin: glancing impact of Mars-sized body on the still-liquid Earth caused enough material, mostly from the mantle, to be ejected to form the Moon. Computer model 5.8 History of the EarthMoon System Copyright 2010 Pearson Education, Inc. 5.8 History of the EarthMoon System Four billion years ago, the Moon had many craters but no maria. By three billion years ago, the maria had formed. Now, they also are covered with craters. Copyright 2010 Pearson Education, Inc. Summary of Chapter 5 Earths structure, from inside out: Core, mantle, crust, hydrosphere, atmosphere, magnetosphere Tides are caused by gravitational effects of Moon and Sun. Atmosphere is mostly nitrogen and oxygen; thins rapidly with increasing altitude. Greenhouse effect keeps Earth warmer than it would otherwise be. Copyright 2010 Pearson Education, Inc. Summary of Chapter 5, cont. Can study interior by studying seismic waves. Crust is made of plates that move independently. Movement at plate boundaries can cause earthquakes, volcanic activity, mountain ranges, and rifts. New crust formed at rifts shows evidence of magnetic field reversals. Earths magnetic field traps charged particles from solar wind. Copyright 2010 Pearson Education, Inc. Summary of Chapter 5, cont. Main surface features on Moon: maria, highlands Heavily cratered No atmosphere and large daynight temperature excursions Tidal interactions responsible for synchronicity of Moons orbit; tidal locking Moon phases Copyright 2010 Pearson Education, Inc. Summary of Chapter 5, cont. The Moons surface has both rocky and dusty material. There is evidence for volcanic activity. The Moon apparently formed as a result of a large object colliding with Earth. Copyright 2010 Pearson Education, Inc. Videos of solar windsolar-winds.htmlstem_highlights/aurora_(astronomy)#p005xg9b Copyright 2010 Pearson Education, Inc. Dec 7. It was on this day in 1972 that astronauts on the Apollo 17 spacecraft took a famous photograph of Earth, a photo that came to be known as "The Blue Marble." Photographs of Earth from space were relatively new."The Blue Marble." The photograph captured on this day thirty-nine years ago was the first clear image of the Earth, because the sun was at the astronauts' back, and so the planet appears lit up and you can distinctly see blue, white, brown, even green. It was taken 2 hours after the craft left earth orbit on its way to the moon. It became a symbol of the environmental movement of the 1970s, and it's the image that gets put on flags, T-shirts, bumper stickers, and posters. The crew of Apollo 17 was about 28,000 miles away from Earth when they took the Blue Marble photo. It was the last time that astronauts, not robots, were on a lunar mission since then, no people have gotten far enough away from Earth to take a photo like it. Copyright 2010 Pearson Education, Inc. Earthrise. The most famous photo of earth, taken by Apollo 8 crew on Christmas Eve, 1968 Copyright 2010 Pearson Education, Inc. The Apollo Programhttps://www.youtube.com/watch?v=awyuMF9rYhQ and https://www.youtube.com/watch?v=CdQFZRJhkCk 9 min from Mercury through Apollo, pretty good.https://www.youtube.com/watch?v=awyuMF9rYhQ https://www.youtube.com/watch?v=CdQFZRJhkCk Apollo 1: accident and 3 deaths on ground Apollo 8: lunar orbit, pics of earth Apollo 11: first landing on moon Apollo 13: accident in transit Apollo 17: last mission to the moon Copyright 2010 Pearson Education, Inc. We do have the ISSNKW-khttp://www.youtube.com/embed/doN4t5 NKW-k Copyright 2010 Pearson Education, Inc. Models of the sky: identify a few 1.Globe 2.Celestial sphere clear plastic 3.Sun-earth-moon orrery 4.Stellarium 5.Solar walk 6.Star walk Individually, prepare a 3 minute demo that teaches us something relevant