Chapter 22outline


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Chapter 22outline

  1. 1. Chapter 22 Origin of Modern Astronomy
  2. 2. Early Astronomy <ul><li>Earth is just one of eight major planets and 3 dwarf planets that orbit our sun. </li></ul><ul><li>Our sun is just one of perhaps 100 billion stars that make up our galaxy the Milky Way. </li></ul><ul><li>The Milky Way is just one of billions of galaxies. </li></ul><ul><li>Where does this knowledge come from?????????? </li></ul>
  3. 3. Ancient Greeks <ul><li>___________ is the science that studies the universe. Astronomy deals with the properties of objects in space and the laws under which the universe operates. </li></ul><ul><li>“Golden Age” of early astronomy (600 B.C. – A.D. 150) was centered in ___________. </li></ul>
  4. 4. Greeks developed <ul><li>The basics of ___________ and ___________ </li></ul><ul><li>Measured the distances of the sun and moon </li></ul><ul><li>Aristotle determined that the Earth was round because it cast a round shadow on the moon. This theory was later abandoned. </li></ul><ul><li>___________ first to calculate the circumference of the Earth….. </li></ul><ul><li>Describe his experiment and figure his mistakes. </li></ul>
  5. 5. Here is how he did it……….
  6. 6. 7.2 0 7.2 0
  7. 7. Then he calculated How much of a circle is ___________ ? ___________ The total distance was? 39,400 km. The actual distance is closer to 40,075 km.
  8. 8. Problems with the solution…… <ul><li>1. </li></ul><ul><li>2. </li></ul><ul><li>3. </li></ul><ul><li>4. </li></ul>
  9. 9. <ul><li>___________ developed star catalogue. He determined the locations of 850 stars, which de divided into six groups according to their brightness. </li></ul><ul><li>He measured the length of the year to within minutes </li></ul><ul><li>He developed a method of predicting the times of lunar eclipses to within a few hours. </li></ul>
  10. 10. ___________ Model <ul><li>___________ centered solar system… outside the solar system the stars traveled within a hollow sphere called the celestial sphere. </li></ul>
  11. 11. ___________ Model <ul><li>___________ centered </li></ul><ul><li>Aristarchus (312 – 230 B.C.) first to believe in this model. </li></ul><ul><li>This model was later proposed by Copernicus (1473 – 1543) and proved by his student Galileo. </li></ul><ul><li>This model was not accepted originally. </li></ul>
  12. 12. Ptolemaic System <ul><li>An attempt to explain planetary movement referred to as ___________ . </li></ul><ul><li>Retrograde motion is the ___________ of a planet. </li></ul><ul><li>How is this possible? </li></ul>
  13. 13. ___________ : <ul><li>Concluded that Earth was a planet. </li></ul><ul><li>He proposed a heliocentric solar system model. </li></ul>
  14. 14. v <ul><li>Built an observatory near Copenhagen. </li></ul><ul><li>He developed and used several instruments made of stone to make calculations. </li></ul><ul><li>Brahe made precise observations about Mars . Later in life he found and assistant by the name of Johannes Kepler. </li></ul>
  15. 15. ___________ <ul><li>Discovered three ___________. </li></ul><ul><li>Astronomical unit – distance from the Earth to the sun or 150,000 kilometers </li></ul>
  16. 16. Three Laws of Planetary Motion <ul><li>All orbits are ___________ in shape </li></ul><ul><li>An ___________ is an almost perfect circle </li></ul>
  17. 17. <ul><li>___________ Law </li></ul><ul><li>Each of these triangles are equal in area </li></ul><ul><li>Can you understand the Earth travels faster as it gets closer to the sun and slower as it moves away from the sun? </li></ul>
  18. 18. <ul><li>___________ Law </li></ul><ul><li>This law ___________ ( its year) of any planet. </li></ul><ul><li>The base unit of measure is the distance from the Earth to the sun which equals 1 astronomical unit or (approx. 150, 000,000 km.) </li></ul><ul><li>Solar distances can be calculated when the periods of revolution (orbit) are known. </li></ul>
  19. 19. T 2 =d 3 <ul><li>Ex. Using Mars </li></ul><ul><li>Mars revolution equals 1.88 years </li></ul><ul><li>The square of this is 3.54 </li></ul><ul><li>The cube root of this is 1.52 </li></ul><ul><li>This means that Mars is 1.52 a.u. from the sun. </li></ul>
  20. 20. Using the formula another way… <ul><li>If you take the distance in a.u. and cube it. </li></ul><ul><li>Then take the square root of that number, you will calculate the period of revolution of the orbiting body. </li></ul><ul><li>Ex. Jupiter is approx. 5 a.u. from the sun </li></ul># 3 then take square root 5 3 = 125 125 = 11.3 years
  21. 21. ___________ <ul><li>His most important contributions were his descriptions of the behavior of moving objects. </li></ul><ul><li>1609 Galileo heard of a Danish lens maker who had devised a system of lenses that could magnify objects. </li></ul><ul><li>Without ever seeing a telescope Galileo constructed his own. </li></ul>
  22. 22. <ul><li>With the aid of his telescope Galileo discovered: </li></ul><ul><li>1. Four satellites orbiting Jupiter. Today these moons are called Galiliean moons. This discovery proved that objects were orbiting another body besides the Earth. </li></ul><ul><li>2. Planets are circular disks. It was believed they were only points of light. </li></ul><ul><li>3. Venus has phases just like the moon. </li></ul><ul><li>4. The moon’s surface was not smooth. </li></ul><ul><li>5. The sun had spots. </li></ul>
  23. 23. ___________ <ul><li>Scientists of the time wondered about two points: </li></ul><ul><li>1. What causes a moving object to continue to move. </li></ul><ul><li>2. What force keeps the bodies in space from traveling in a straight line out into space. </li></ul><ul><li>Although others had theorized the existence of such a force, Newton was the first to formulate and test the law of universal gravitation. </li></ul>
  24. 24. <ul><li>According to Newton, every body in the universe attracts every other body with a force that is directly proportional to their masses and inversely proportional to the square of the distance between their centers of mass. </li></ul><ul><li>Example: The gravitational force decreases with distance, so that two objects 3 kilometers apart have 32, or 9, times less gravitational attraction than if the same objects were 1 kilometer apart. </li></ul>
  25. 25. <ul><li>The greater the mass of the object, the greater is its gravitational force. </li></ul><ul><li>(discuss the difference between mass and weight) </li></ul><ul><li>___________ being the total amount of matter an object contains. </li></ul><ul><li>___________ is the force of gravity upon an object. </li></ul>
  26. 26. <ul><li>Earth moves forward in its orbit about 30 kilometers per second. </li></ul><ul><li>During the same second, the force of gravity pulls it towards the sun about 0.5 centimeters. </li></ul><ul><li>Newton concluded that it is the combination of Earth’s forward motion and its “falling” motion that defines its orbit. </li></ul>
  27. 27. Newton’s laws of Gravity <ul><li>An ___________ (force) in motion will stay in motion until another ___________ (force) acts upon it. </li></ul><ul><li>The larger the mass, means that it will have stronger gravity . (used to calculate escape velocities) </li></ul><ul><li>For every action there is an ___________ & ___________ reaction </li></ul>
  28. 28. The Earth-Moon-Sun System <ul><li>Stonehenge……. Lets take a look </li></ul>
  29. 29. Motions of Earth <ul><li>The two main motions of Earth are ___________ (spin) and ___________ (orbit) . </li></ul>
  30. 30. Revolution is …….. <ul><li>is the motion of a body, such as a planet or moon, along a path around some point in space. </li></ul><ul><li>Earth’s average speed is 107,000 kilometers per hour. </li></ul><ul><li>Our average distance from the sun is 150,000,000 kilometers. However, all orbits are elliptical so…. </li></ul>
  31. 31. <ul><li>Earth’s ___________ is when the Earth is closest to the sun about 147,000,000 kilometers. This occurs on January 3rd each year. </li></ul><ul><li>Earth’s ___________ is when Earth is at is farthest point from the sun about 152,000,000 kilometers. This occurs on July 4th each year. </li></ul><ul><li>Is this why we have seasons???????? </li></ul>
  32. 32. <ul><li>The apparent annual path of the sun against the backdrop of the celestial sphere is called the ___________. </li></ul><ul><li>The planets and moon travel along the same plane as Earth, so their paths on the ___________ lie near the ecliptic. </li></ul>
  33. 34. Earth’s axis …… <ul><li>is tilted on this plane ___________ to the ecliptic. </li></ul><ul><li>This tilt creates ___________. </li></ul>
  34. 35. <ul><li>When the apparent position of the sun is plotted on the celestial sphere over a period of a year’s time, its path intersects the celestial equator at two points. </li></ul><ul><li>These intersect points are spring (March 20 or 21) and fall (Sept. 22 or 23). </li></ul>
  35. 36. <ul><li>When the sun is 23.5 0 north of the equator….. </li></ul><ul><li>___________ occurs. </li></ul><ul><li>When the sun is 23.5 0 south of the equator….. </li></ul><ul><li>___________ occurs. </li></ul>
  36. 37. Procession <ul><li>The Earth has another very slow motion called procession, which is a slight movement, over 26,000 years. </li></ul><ul><li>The Earth’s axis traces a circle in space similar to the wobble of a spinning top. </li></ul>
  37. 38. <ul><li>At the present time the northern axis points to Polaris, which is referred to as the North Star. </li></ul><ul><li>In the year 14,000 our northern axis will point to Vega, which will then become our north star. </li></ul><ul><li>Then in the year 28,000 Polaris will again be our north star. </li></ul>
  38. 40. Rotation ……. <ul><li>Rotation results in day and night. </li></ul><ul><li>It has become a standard of measuring time. </li></ul><ul><li>Each rotation equals about 24 hours. </li></ul><ul><li>Notice that it says about 24 hours! </li></ul>
  39. 41. <ul><li>___________ is the time it takes for the Earth to make one complete rotation (360 degrees) with respect to a star other than our sun. </li></ul><ul><li>A sidereal day is equal to ___________ hours ___________ minutes and ___________ seconds . </li></ul>
  40. 43. <ul><li>___________ is good for determining time. </li></ul><ul><li>Sidereal is used to determine the ___________ Earth is to be at the beginning of each season. </li></ul>
  41. 44. Earth-Sun Motion <ul><li>The Earth, sun, and the rest of the solar system travel through space at a speed of 20 kilometers per second towards the star, Vega. </li></ul><ul><li>Our solar system also revolves around the galaxy. </li></ul><ul><li>The trip takes 230 million years and travels at speeds approaching 250 kilometers per second. </li></ul>
  42. 45. <ul><li>Galaxies are also in motion. </li></ul><ul><li>Earth is presently approaching the Great Galaxy in Andromeda. </li></ul>
  43. 46. Motions of the Earth-Moon System <ul><li>Average distance to the moon is 384,401 kilometers. </li></ul><ul><li>___________ (farthest point in its orbit) and ___________(closest point in its orbit). </li></ul><ul><li>Lunar phases are a result of the motion of the moon and the sunlight that is reflected from its surface. </li></ul>
  44. 47. Lunar Motions <ul><li>The moon cycle of phases takes ___________ days . </li></ul><ul><li>One orbit of the moon around the earth takes ___________ days </li></ul><ul><li>One rotation on the moon takes ___________ days </li></ul><ul><li>Something doesn’t seem to add up!!!!!!!!!!!!! </li></ul><ul><li>What does this all mean???? </li></ul>
  45. 48. <ul><li>If the orbit and rotation of the moon are the same (27.3 days), that means? </li></ul><ul><li>___________ </li></ul><ul><li>Why then does it take the moon longer to go through its phases? </li></ul><ul><li>It must “___________” to where the ___________ to be since the Earth is orbiting the sun. </li></ul>
  46. 49. Because the moon must catch up to the Earth each day, it rises 50 minutes later each night .
  47. 50. Phases of the Moon <ul><li>Phases result from the motion of the moon and the sunlight that is reflected. </li></ul><ul><li>For the purposes of this class we will only use the following phases: </li></ul><ul><li>___________ - dark </li></ul><ul><li>___________ – lighted side grows larger </li></ul><ul><li>___________ </li></ul><ul><li>___________ – shadowed side grows larger </li></ul>
  48. 52. Eclipses <ul><li>Two types: </li></ul><ul><li>________ </li></ul><ul><li>________ </li></ul>
  49. 54. <ul><li>________ occur with new moon phase </li></ul><ul><li>________ occur with full moon . </li></ul><ul><li>During a new-moon or full moon phase, the moon’s orbit must cross the plane of the ecliptic for an eclipse to occur. </li></ul><ul><li>There are usually ________ that occur in two sets. One lunar and then a solar, then 6 months later another lunar and solar. </li></ul>
  50. 55. <ul><li>During any given year there are not more than ________ eclipses. </li></ul><ul><li>Solar eclipses last about 7 minutes in any given area. </li></ul><ul><li>The size of the shadow is approximately 275 kilometers wide or about the size of South Carolina. (FYI) </li></ul><ul><li>The next total solar eclipse will occur August 21, 2017. </li></ul>
  51. 56. Earth’s Moon <ul><li>Moon characteristics: </li></ul><ul><li>Size 3475 kms. Or about ________ that of Earth </li></ul><ul><li>6 Apollo missions landed on the moon between 1969 and 1972 </li></ul><ul><li>Moon’s density is 3.3 which is less than the 5.5 of Earth rocks. </li></ul><ul><li>Gravity is ________ of Earth </li></ul>
  52. 57. Lunar Surface <ul><li>No volcanism </li></ul><ul><li>________ – most craters were produced by the impact of rapidly moving debris. </li></ul><ul><li>A meteoroid 3 meters in diameter can make a crater 150 meters wide. </li></ul><ul><li>Larger craters like Kepler and Copernicus were formed with the impact of bodies 1 kilometer or more in diameter. </li></ul><ul><li>________ – debris splash marks near the crater. </li></ul>
  53. 61. Rays with craters
  54. 62. <ul><li>________ – or mountain peaks. </li></ul><ul><li>The highest is near 8 kilometers in height or just 1 kilometer short of Mt. Everest. </li></ul>
  55. 63. ________ – (seas) name by Galileo <ul><li>Relatively dark smooth areas on the moon’s surface. </li></ul><ul><li>Maria formed from ancient beds of basaltic lava, originated when asteroids punctured the lunar surface, letting magma bleed out. </li></ul><ul><li>These lava flows are often 30 meters thick. </li></ul><ul><li>Long channels called ________ are associated with maria. They may be the remains of ancient lava flows or lava tunnels then caved in. </li></ul>
  56. 65. <ul><li>________ – lunar regolith, which is a soil like layer on the moon. It is composed of igneous rocks, glass beads, and fine lunar dust. </li></ul>
  57. 67. Lunar History <ul><li>Most accepted lunar formation model: </li></ul><ul><li>The origin of the moon occurred when the solar system was forming, a body the size of Mars impacted the Earth. </li></ul><ul><li>A portion of the liquefied material entered Earth’s orbit where it combined to form the moon. </li></ul>
  58. 68. Evidence <ul><li>1. Ejected material would have been iron poor and so is the moon. </li></ul><ul><li>2. The ejected material would have stayed in orbit long enough to loose its water. </li></ul>
  59. 70. <ul><li>The moon evolved in three stages: </li></ul><ul><li>The original crust meaning ________ </li></ul><ul><li>maria basins </li></ul><ul><li>rayed craters </li></ul>
  60. 71. <ul><li>Continued impact of meteoroids combined with radioactive decayed materials, generated enough heat to melt the moon’s outer shell and possibly the inner as well. </li></ul><ul><li>The highland areas are estimated to be 4.5 billion years old. </li></ul>
  61. 72. <ul><li>The maria basins are younger than the highlands and in some places over lap some highland areas. </li></ul><ul><li>The last features to form were the rayed craters. </li></ul><ul><li>Most of the old craters are ray-less . </li></ul>