Astronomy NC 2014


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Developed in 2014 for NC ES/Environmental high school curriculum

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Astronomy NC 2014

  1. 1.  You will receive a list of unit vocabulary at the top of every unit note packet!  How you choose to complete the vocabulary is up to you!  It should be completed in your science notebook or stored in your binder and will be checked for completion on the day it is due. [10 points]  Expect a vocabulary test approximately 1 week after you receive the list.
  2. 2. Unit 1 The study of stars and space.
  3. 3. Big Bang
  4. 4. • The universe is expanding o How do we know this? • In the late 1920’s, Edwin Hubble discovered that All galaxies were “redshifted” when viewed from Earth. • This meant that all galaxies were moving away from Earth and each other, and thus, the universe must be expanding. • Learn to annotate!
  5. 5. • • • All matter and energy in the universe was once condensed into a single point 13.8 bya Moments after the Big Bang, the universe was very hot and dense o Protons, neutrons, and electrons formed o Hydrogen formed o There was enough energy to start nuclear fusion  Helium formed
  6. 6. • Evidence o Background radiation  Space! o There should be no heat at all (0K) o Scientists have measured space; 3K (Background radiation exists) o Composition of matter in the universe 74% hydrogen  24% helium 
  7. 7. Expansion of the Universe
  8. 8. A. Electromagnetic Energy 1. 2. The sun is the major energy source for weather changes in the atmosphere and many of the changes occurring at Earth’s surface. Energy from the sun comes in many different wavelengths.
  9. 9. The number of wave crests passing any given point in a unit of time High speed = High frequency
  10. 10.  Study of the properties of light that depend on wavelength.  light given off by stars has many colors  The light appears white Spectroscope: Instrument used to break up light from a star into its characteristic colors
  11. 11. Continuous Spectrum is an uninterrupted band of color from red to purple
  12. 12.  Absorption Spectrum appears continuous, but with dark lines running through it at various wavelengths  Spectra of most stars
  13. 13.  Emission (you will need to cross out absorption in  your notes) spectrum is a series of bright lines of particular wavelengths depends on the gas that produced them  bright lines appear in the exact location as the dark lines that are produced by the same gas in an absorption spectrum
  14. 14.  Each element or compound in its gaseous form produce a unique set of spectral lines  Spectral lines act as “fingerprints” used to identify elements present in the star’s composition ex) The SUN has thousands of dark lines & more than 60 elements have been identified by matching these lines with those elements known on Earth
  15. 15. • The Doppler Effect o o o The change in frequency of a wave an observer relative to its motion Moving toward you: Waves are compressed together Moving away: Waves are stretched
  16. 16. • Redshift o When the light of a distant object (star, planet, etc.) is viewed through a prism, the spectrum is not continuous
  17. 17. • Redshift o When the light of a distant object (star, planet, etc.) is viewed through a prism, the spectrum is not continuous o Black lines appear: Absorption lines  o Determine which elements are present When the object is moving away from us, the absorption lines are shifted toward the red end of the spectrum (stretched): Redshift!
  18. 18. Using the spectroscope, astronomers can determine whether a particular object is moving toward Earth or away from Earth
  19. 19. • Hubble’s Law: The further an object is from Earth, the faster it is moving o If a galaxy is twice as far from Earth as another, it is moving twice as fast
  20. 20. Structure of the Sun
  21. 21. • • • Our sun is just one of billions of stars in the Milky Way galaxy. Only star whose surface we can study. Through spectroscopic analysis of the sun, scientists know that most of the known elements are found in the sun o Hydrogen makes up 74% of the sun’s mass o Helium makes up 24%
  22. 22. • Sunspots: “Dark” areas on the sun o o o “Cool” areas The magnetic field breaks through the surface, causing a disruption in heat transfer The number of sunspots varies every 11 years. This is known as the solar cycle.
  23. 23. • The core o Nuclear fusion
  24. 24. Life Cycles of Stars
  25. 25. • A Star is Born
  26. 26. • • A star’s “life cycle” can last billions of years. The following slides describe the general phases in stellar evolution
  27. 27. Nebula • Dark, cool clouds of interstellar gas and dust. • Often referred to as “stellar nurseries.” • Stars begin to form as gas and dust collide.
  28. 28. Protostar • Developing star • Not yet hot enough for fusion reactions (10x106 K)
  29. 29. Main Sequence Star • Hydrogen to Helium fusion has begun! • The hotter, larger stars burn H2 fastest. • This stage makes up 90% of a star’s “life.”
  30. 30. Hertzsprung-Russell Diagram • E. Hertzsprung and H. Norris Russell studied the relation between the absolute magnitude (or luminosity) and spectral types (or surface temperature) of stars. • The diagram showing these two variables is known as HR diagram. • The HR diagram represents a major step towards an understanding of stellar evolution.
  31. 31. Earth’s Place in the Universe
  32. 32. Universe Our Milky Way Galaxy is one of billions of galaxies in an expanding universe
  33. 33. Milky Way Galaxy • Our Sun/solar system is one of an estimated 180 billion stars making up this spiral galaxy
  34. 34. Our Solar System Earth – a small dense rocky planet, one of 8 planets that orbit the sun AND – the only one we know of that has LIFE as we know it……
  35. 35. Models of the Universe A. Geocentric Model 1. About 2000 years ago, the Greek astronomer, Claudius Ptolemy developed a detailed model of the universe based on the idea of revolving spheres.
  36. 36. Models of the Universe 2. In this model of the universe, Earth was at the center, and all heavenly bodies moved around Earth in Perfect circles.
  37. 37. 3. Ptolemy’s Geocentric model, as illustrated on the next page, can be summarized as follows: a. Earth is located in the center and does not move. b. The stars are located on a transparent sphere that rotates once each day from east to west around Earth.
  38. 38. c. The Sun, the Moon and each planet are carried by separate spheres of different sizes. d. Each planet is located on an epicycle that also rotates. This explained retrograde motion – the apparent backward motion of planets.
  39. 39. d. This model was accepted for almost 1400 years because it explained celestial observations made from Earth and……… seemed obvious. • However – f. it The geocentric model does NOT explain terrestrial (Earth) observations such as: 1. The movement/rotation of a pendulum’s direction. 2. The curvature of the paths of projectiles, winds & ocean currents.
  40. 40. B. Heliocentric Model In the 1500’s, a new model of the universe was proposed in a book by the Polish astronomer Nicholas Copernicus. • In this model of the universe, the sun was the center. 2:08
  41. 41. Heliocentric Model Copernicus’ heliocentric model can be summarized as follows: 1. The Sun is located in the center of the system and does NOT move. 2. The stars are located on a stationary/unmoving transparent sphere. The sphere is a great distance from the sun. 3. The planets, including Earth, move in circles around the sun. 4. The Moon moves in a circle around Earth. 5. Earth rotates on its axis from west toward east each day.
  42. 42. However….. Copernicus’ heliocentric model does NOT explain the apparent cyclic variations in the size of the Sun, and the cyclic variation in orbital speeds of the planets. This is because in the heliocentric model, the planets orbit the sun in perfect circles.
  43. 43. C. Kepler’s Heliocentric Model 1. In 1609, Johannes Kepler published a book which included his first 2 “Laws of Planetary Motion”. These laws explain why the apparent size of the sun changed, and why the speed of a planet changes as it orbits the Sun.
  44. 44. a. Kepler’s First Law • The orbit of each planet is an ellipse with the sun at one focus and an imaginary point in space at the other focus.
  45. 45. An Ellipse – draw the parts in your notes  An ellipse looks like an oval, or squashed circle.  The longest line drawn from one end of the ellipse (through the center) to the other side is called the major axis.
  46. 46. √ Eccentricity • Eccentricity (e) = the “out of roundness” shape of the ellipse given by the ratio of the distance between the two foci and the length of the major axis. •e = distance between foci Length of Major Axis The eccentricity of a circular orbit is zero, and can range from zero to less than one for an ellipse.
  47. 47. 2. Eccentricity d. Relationship: As the distance between the focal points increase, the shape of the ellipse becomes more oval (Circle = 0)
  48. 48. B. Kepler’s Second Law  describes the fact that a planet moves fastest in its orbit when it is nearest the Sun. Maximum speed Decreasing speed  Area A = Area B = Area C Minimum speed
  49. 49. B. Kepler’s Second Law 1. Perihelion = point in orbit nearest to sun 2. Aphelion from sun = point in orbit furthest
  50. 50. C. Kepler’s Third Law • The further a particular planet is from the sun, the longer it’s period (time) of revolution. • 1. Farther planets have longer orbital paths • 2. Farther planets have slower orbital paths
  51. 51. D. Sir Isaac Newton 1. Newton’s Laws of Gravity First Law a) All objects with mass will be acted on by gravity and will pull all other objects with a certain gravitational force.
  52. 52. Newton’s Laws of Gravity b) Newton’s Second Law The mass of an object will determine the amount of gravitational force that object possesses. • The greater the mass, the greater the gravitational force.
  53. 53. Newton’s Laws of Gravity c) Third Law The gravitational force between 2 objects changes as the distance between them change. As the distance increases, gravitati onal pull will decrease.
  54. 54. 2. Gravity and Inertia
  55. 55. a. Newton’s Law of Inertia States that a body in forward motion will continue in forward motion unless acted on by an outside force. Inertia Gravity Stable Orbit
  56. 56. B. Gravity and Inertia  Inertia – causes a planet to move in a straight line.  Gravity – pulls a planet toward the sun.
  57. 57. Rotation • The spinning of a celestial body (Earth) on an imaginary axis
  58. 58. Rotation A. Earth’s Direction of Rotation: WEST to EAST 2. Angular Rate of Rotation: THINK – one complete rotation a. 360 degrees b. 24 hours Rate = 3600/24 hours = 150/hour
  59. 59. B. Effects of Earth’s Rotation 1. Day and Night
  60. 60. B. Effects of Earth’s Rotation 2. Apparent daily motion of the sun a. Earth rotates from WEST to EAST b. Sun “appears” to move in an arc from EAST to WEST
  61. 61. Earth is NOT a perfect sphere. It is an oblate spheroid – slightly wider across the equator (due to its rotational spin) Earth‘s axis is not stable. It moves/wobbles (like a top). This is known as precession. It’s very slow - 26,000 years to complete one cycle. Within the precession are additional motions known as nutations. These are smaller motions back and forth as the precession occurs.
  62. 62. V. Revolution • The orbiting of one celestial body around another celestial body. A. Earth’s Angular Rate of Revolution 1. 360 degrees 2. 365 days 3. Rate = 3600/365 days ~ = 10/day
  63. 63. B. Effects of Earth’s Revolution 1. Nighttime constellations change in a yearly cycle. 2. Constellation – groups of stars that form patterns of imaginary things such as animals, legendary heroes, and mythological gods
  64. 64. 3. Seasons – a yearly cycle
  65. 65. 5. Seasons of the Year A. Causes: 1. Revolution - Earth revolves around the sun 2. TILT - Earth is tilted/inclined on axis 23 1/2o 3. Parallelism of Axis - Earth’s axis always points in the same direction.
  66. 66. B. Earth’s axis is tilted 23.50 relative to the plane of it’s orbit. • Draw and label your diagram according to the diagram at the right. Be sure to name the equator, the Tropic of Cancer and Capricorn and note where we live.
  67. 67. C. The apparent path of the sun changes with the seasons and with latitude. N.C. 35.5 degrees North Latitude
  68. 68. D. Length of Daylight (duration of daylight) – changes with seasons and with latitude.
  69. 69. E. Factors affecting Insolation 1. Shape of the Earth (spherical) 2. As latitude increases, the angle of insolation decreases, and the intensity of insolation decreases.
  70. 70. 3. Season of the Year a. As Earth travels along its orbital path around the sun, the angle of insolation at a given latitude changes with the seasons. This depends on how far a given latitude is from the direct rays of the sun. The direct rays migrate between the Tropic of Cancer (north) and the Tropic of Capricorn (south).
  71. 71. 4. Time of Day a. The angle of insolation changes in the course of one day. Maximum intensity occurs at Noon.
  72. 72. b. Looking South • The shadow of a vertical pole indicates how the angle of insolation changes during the day. The higher/greater the angle of insolation, the shorter the shadow, and the greater the intensity of insolation.
  73. 73. VI The Moon A.The moon is a natural satellite of Earth. 1. Luna – Latin for moon 2. Diana – Roman goddess of the moon
  74. 74. B. Physical Properties of the Moon 1. Size a. Diameter: 2160 miles b. Compared to Earth Diameter of Moon = 2160 = 1 Earth 2. 8000 4 Gravity a. 1/6 the gravity of Earth b. This is because the Moon has – less mass
  75. 75. 2. Atmosphere a) The Moon has No atmosphere, so radiation from sun strong b) Gravity too weak so gases escape into space. c) Without an atmosphere radiation from the sun is INTENSE! d) Frozen water may exist at the Moon’s polar regions, but none in liquid form
  76. 76. 3. Temperatures a. 240oF on the lighted side b. - 240oF on the far side c. These large temperature extremes or differences exist because NO atmosphere to transfer heat.
  77. 77. 4. The Moon’s Revolution a. Period of Revolution b. 1 month OR 29.5 days c. The moon revolves around Earth in an elliptical orbit with the Earth at one focus. d. This causes the moon’s apparent diameter/size to change in a cyclic manner.
  78. 78. 5. Phases of the Moon a. The phases of the moon are caused by the moon’s revolution around Earth. b. Our Earth view of the changing illuminated part of the moon’s surface that face’s Earth.
  79. 79. c. Waning moon - the decrease in light (on the left), away from being a full moon to new moon, is called a.
  80. 80. d. waxing moon - as the moon increases towards becoming a full moon.
  81. 81. Phase #1 New Moon When the moon is in between the sun and the Earth, we cannot see the moon. This part of the moon is in the shade.
  82. 82. 6. Moon Rotation b. c. Does that mean the moon doesn't rotate? YES it does --one rotation for each revolution around Earth!
  83. 83. 7. Lunar Eclipse a. An eclipse of the Moon can only take place at full moon and only if the Moon passes through some portion of the earth’s shadow. The shadow is actually composed of two (2) cone-shaped components, one inside the other. The outer or penumbra shadow is a zone where some portion of the sun’s rays are blocked. In contrast, the inner or umbra shadow is a region devoid of all direct sunlight.
  84. 84. 8. Solar Eclipse a. A solar eclipse occurs when the moon passes directly between the Earth and sun. b. New Moon are the only time solar eclipses can occur.
  85. 85. 10. Tides a. Tides are the alternate rising and falling of the sea. b. This is caused by the Moon’s gravitational pull. c. The rising of tides is affected by the position and distance of moon! d. The period from high tide to high tide is 12 hours and 12 minutes. e. Tides are a CYCLIC