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Review#14 astronomy
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  • 1. L.O: CELESTIALOBSERVATIONS, EARTH’S ROTATION& REVOLUTION, ELLIPTICAL ORBITSOF THE PLANETS, THE MOON, THESTARS & THE UNIVERSE.
  • 2. Celestial means “of the sky”Celestial objects areall the objects in thesky.(the planets, stars,moon, sun etc)
  • 3. All celestial objects appearto move across the sky ata rate of 150 per hour.
  • 4. Viewed from the north polar, allconstellations appear to rotate aroundPolaris.Polaris, herein the center
  • 5. EARTH HAS NIGHT ANDDAY BECAUSE IT ROTATESON ITS AXIS.
  • 6. THE SIDE FACING THE SUNIS “DAY”. THE SIDE AWAYFROM THE SUN IS “NIGHT”
  • 7. EARTHTAKES 24HOURSTOROTATE!
  • 8. EARTHMOVE 15 0DEGREESEVERYHOUR.150 X 24=3600DEGREES
  • 9. EVIDENCE THATEARTH ROTATES:
  • 10. THE TWO MAIN EVIDENCE OFEARTH’S ROTATION ON ITS AXIS:•FOUCAULT’SPENDULUM•THE CORIOLISEFFECT.
  • 11. For every hour, the Sun appears tomove 15 0 degrees per hour!
  • 12. Night and day are caused byEarth rotating around the sun!!!!!
  • 13. The seasons:
  • 14. There are four important days thatyou must know. What are they?
  • 15. There are four important days thatyou must know. What are they?
  • 16. The parts that are “leaning” towards theSUN get the vertical (direct) rays haveSUMMER
  • 17. The parts that are “leaning” away fromthe SUN get the vertical (direct) rayshave WINTER
  • 18. What exact day is this? How do youknow?
  • 19. JUNE 21st, the first day of summer in theNorthern hemisphere. Because the North isleaning towards SUN!
  • 20. What day is this? How do youknow?
  • 21. DECEMBER 21st, first day of winter innorth. Because north leans away fromsun.
  • 22. THIS DIAGRAM SHOWS THESUN’S PATH IN NEW YORK STATE
  • 23. The Heliocentricmodel
  • 24. The Heliocentric model• The sun is thestationarycenter. All theplanets includingEarth revolvearound the sun.
  • 25. The heliocentric model explainedretrograde motion: why planetsappear to wander backwards acrossthe sky.
  • 26. The solar system(planets part 1)
  • 27. The “solar system”: is theSun, the 8 planets, the “dwarf”planets, all the moons & every othercelestial object that revolves aroundSol.
  • 28. Planets (pt 2):Our star systemhas 8 planets.
  • 29. There are two classesof planets in our solarsystem: terrestrial andjovian.
  • 30. Terrestrial planets:• The “earth-like” planets. “Terra” is anothername for Earth.• Mercury, Venus, Earth & Mars.• Terrestrial planets are small, “rocky”, highdensity & orbit close to the sun.• Someday, humanity may colonize the otherterrestrial planets for the benefit ofHumankind!
  • 31. Mercury today
  • 32. Venus earth’s “twin”
  • 33. Earth: the“goldilocks” planet• Not too hot, nottoo cold.• The only planetthat can haveliquid water onits surface.• The only planetwe know thathas life.
  • 34. Earth moves in two ways:Rotation:The Earth spinning onits north-south axis.The earth rotates at 150per hour. After 24hours, it has turned3600 (one full turn)
  • 35. Earth moves in two ways:Revolution:The Earth’s slightly ellipticalorbit around the Sun.The Earth revolves about10 per day. After 365 1/4days, it has made a fullorbit around Sol.Rotation: earth rotates onits axis.
  • 36. The 2 main evidence of earth’srotation:1.Foucaultspendulum2.The Coriolis effect
  • 37. a Foucaults pendulum seems tochange directions is one proof ofEarth’s rotation.
  • 38. The coriolis effect: the winds seem tocurve proof that earth rotates.
  • 39. Jovian planets• The “Jupiter-like” planets. Jove was anothername for Jupiter.• Jupiter, Saturn, Uranus, Neptune.• They are very large, low density, madecompletely of gases such as Hydrogen, helium,methane & ammonia.• They used to all be called: “the gas giants”• Jupiter and Saturn are called the “gas giants”• Uranus and Neptune are the “ice giants”
  • 40. Jupiter: a failed sun?
  • 41. Saturn: very low density. Would float inwater!
  • 42. Uranus
  • 43. Neptune
  • 44. Open to ESRT page 15
  • 45. The sun• The sun is middle aged mainsequence star. 4.6 billion yearsold.• The sun is powered by nuclearfusion: Hydrogen atoms fusingtogether.
  • 46. stars•All stars use nuclear fusionto “power” themselves.•Stars come in many colors:red, yellow (our sun), white,blue, (& probably brown)
  • 47. stars•Stars have differentluminosity (brightness)•Stars have differenttemperatures
  • 48. You are responsible for this page
  • 49. Circles &****ellipses
  • 50. ***The orbits of the planetsare not perfect circles!
  • 51. a circle is a perfectly round shape withone central point called a focusThefocus
  • 52. This is an ellipse: **an ellipse is a ovalshape with two foci (two “centers”)
  • 53. ellipses are described as“eccentric”.Round but not a perfect circle.
  • 54. ** ellipses have two axes, a **major axisand a minor axis.
  • 55. the planets do NOT orbit the sun in perfect circles. Theplanets revolve around the sun in elliptical orbits(oval orbits), with sun being one of the foci.
  • 56. This is a perfect circle!This is an ovalThis is an ovalWhich is more “oval”?
  • 57. You are now responsible for thisformula.
  • 58. On the performance part of the regents, youwill calculate the eccentricity of the orbit ofan asteroid….
  • 59. Celestial objects orbital speed isfastest when close to the sun.
  • 60. Gravity: the force ofattraction between bodies.
  • 61. Larger mass objects have strongergravity than smaller mass objects.
  • 62. Evidence of Earth’s revolvingaround the SUN:•Change in the Sun’sangular diameter.•The cyclical seasonalchange in the Zodiacconstellations.
  • 63. 1.Angular diameter:proof Earth revolvesaround the Sun
  • 64. the sun is very large but looks “tiny”because it is far away.
  • 65. Proof #2: that Earthrevolves around thesun. The yearly changein the zodiac.
  • 66. The constellations of the zodiacappear to move because Earth ismoving around the Sun!!!
  • 67. Questions: name the two “R”ways Earth moves.Earth rotates and Earthrevolves.
  • 68. Earth rotates(spins) on itsaxis.The earth rotatesat 150 per hour.After 24 hours, ithas turned 3600 .Rotation givesEarth night andday(one full turn)
  • 69. Revolution:*Earth revolves around the Sun inslightly elliptical orbit.* Earth revolvesabout 10 perday. After 3651/4 days, it hasmade a full orbitaround Sol.
  • 70. The moon:
  • 71. The moon is Earth’sonly natural satellite.
  • 72. The moon is a “satellite” of Earth because itrevolves around Earth.Similarly, Earth is satellite of the Sun, becauseEarth revolves around the SUN!
  • 73. The moon takes 27 1/3 days tocomplete one revolution aroundEarth (sidereal month)
  • 74. These are the Lunar phases:
  • 75. the Sun’s light rays are always illuminatingone half of the Moon. That is why someparts look lit & some parts look dark.
  • 76. As the Moon revolves around Earth,an Earth observer sees varyingamounts of the illuminated portion ofthe Moon.
  • 77. The Moon takes 29 1/3 days tocomplete a phase cycle from one newmoon to the next new moon.(called asynodic or lunar month)
  • 78. This is the Earth-Moon system viewedfrom space. what phase is A?
  • 79. what phase is B?
  • 80. what phase is C?
  • 81. what phase is D?
  • 82. what phase is E?
  • 83. A tide is a rise in the Earth’s waterlevels caused by the Moon and Sun’sgravity.
  • 84. We have tides because the Moon’sgravity and the Sun’s gravity are pullingon Earth’s oceans.
  • 85. Both the Moon’ and the Sun’s gravityare pulling on Earth’s oceans ALL thetime…..
  • 86. Spring tides andNeap tides:
  • 87. Spring tides: the Sun and Moon’sgravity are pulling TOGETHER.
  • 88. Spring tides happen at the FULL moonor the NEW moon, when the Sun andMoon pull together
  • 89. What do you notice?
  • 90. The tides are cyclical: a high tide tolow tide is ~ six hours.
  • 91. *** a high tide to another high tide is~ 12.5 hours.
  • 92. *** a high tide to another high tide is~ 12.5 hours.
  • 93. A solar eclipse!
  • 94. An “eclipse” is when theSun is blocked by theMoon or the Earth,causing a shadow to becasted.
  • 95. solar eclipse: the moon blocksthe sun and casts a shadow onEarth.
  • 96. solar eclipse: the moon blocksthe sun and casts a shadow onEarth.
  • 97. Lunar eclipse:
  • 98. Lunar eclipse: the Earth blocks thesunlight and casts a shadow on themoon.
  • 99. Eclipses can only be seen overcertain parts of the earth
  • 100. Eclipses can only be seen overcertain parts of the earth
  • 101. Eclipses are rare because theMoon, Earth & Sun must be aligned.
  • 102. The stars
  • 103. Astronomers have learned that thereare many kinds of stars!.
  • 104. stars with different colors, differentsizes, different luminosities (brightness)
  • 105. This is the H-R diagram.
  • 106. The H-R diagram is a graph that plotthe stars’ temperature against theirluminosity.
  • 107. Open to ESRT page 15.
  • 108. You are responsible for this page. Youmust know how to read it
  • 109. Luminosity is “brightness”
  • 110. Surface temperature of stars
  • 111. As luminosity increases, temperatureincreases
  • 112. color of stars
  • 113. Mass (size) of stars
  • 114. Earths place inthe universe:
  • 115. During the scienctific revolution (therenaissance), Copernicus, Kepler, Galileo& Newton developed the heliocentricmodel: which showed that Earth is not thecenter of the universe; Earth revolvesaround the sun.
  • 116. By the early 20th century, peoplerealized that our sun is only one ofbillions of other stars in the milky waygalaxy!
  • 117. definition:Galaxy: A mass ofbillions of stars. Ourhome galaxy is called“the milky way”
  • 118. A typical spiral galaxyThese arecalledspiralarms
  • 119. The universe has countlessbillions of galaxies!
  • 120. definition:The universe is :All ofexistence, all ofcreation, everything.
  • 121. 3) The Milky Way Galaxy is in theUniverse
  • 122. How space distances aremeasured:Space distances are sovast, new units of measurehad to be created to measurespace distances:1.The light-year2.Astronomical units (AU)
  • 123. The big bang!
  • 124. The universe is 13.7 billion years old. Itformed in an “explosion” called “the BigBang”. How do we know this?
  • 125. The big bangtheory
  • 126. Big bang theory• Developed by astronomers, who builtupon Hubble’s discoveries.• the Universe formed from a singleinfinitely dense particle called a“singularity” that “exploded” 13.7billion years ago.• This explosion is why the universe isexpanding.
  • 127. Two evidence of the bigbang:1.***The “red shift” of light.2.The cosmic microwavebackground radiation.
  • 128. ***The red shift oflight:
  • 129. ** a celestial object moving away fromus, shows light waves that arestretched toward the red end of thevisible light spectrum: “red shifted”
  • 130. red shifting is the may evidence thatthe universe is expanding. The furtheran object is from us, the redder it is.
  • 131. Astronomers know that the universe isexpanding because the galaxies arered shifting.
  • 132. beforeafter
  • 133. The object is moving away from us
  • 134. This celestial object has red shifted soit is moving away from us.
  • 135. Which is the oldest? Which is theyoungest?