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Astronomy

Astronomy. Environmental Science. Astronomy is the science that studies the universe. Astronomy deals with the properties and laws of objects in space. The universe is made up of galaxies. There are billions of galaxies in our universe. . Our galaxy is called the Milky Way.

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Astronomy

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  1. Astronomy Environmental Science

  2. Astronomy is the science that studies the universe.

  3. Astronomy deals with the properties and laws of objects in space.

  4. The universe is made up of galaxies. There are billions of galaxies in our universe.

  5. Our galaxy is called the Milky Way

  6. Galaxies are made up of Solar Systems centered with stars.

  7. There areeightplanets andfoursmaller bodies (dwarf planets) that orbit the center of our solar system, the sun.

  8. Milky Way Star Map

  9. Moon “Beach” Activities

  10. The Ancient Greeks

  11. Scientists have been researching the sky for almost 3000 years! • Early astronomy was centered in Greece.

  12. The “Golden Age” of Astronomy in Greece: (600 B.C. – 150 A.D.) • Used philosophical arguments and observation.

  13. Greeks developed Geometry and Trigonometry to measure planet size and distances. • Aristotle (384-322 B.C.) believed that the Earth was round because of the curved shadows it formed on the moon. Idea abandoned in Middle Ages.

  14. Early Greeks use philosophy, personal observations and geometry to make astronomical theories.

  15. Famous Greek Astronomers

  16. Aristotle: concluded the earth is round because the shadow the earth casts on the moon is curved.

  17. Aristotle’s Belief (Geo-centric)

  18. Eratosthenes (aka: Big Head): determined the size of the earth

  19. Hipparchus: determined the length of the year & location of many stars

  20. Early Greeks believe in a Geocentric Model

  21. In reality, the solar system is a Heliocentric Model Aristarchus first proposed the heliocentric model, but no one believed him.

  22. Ptolemy summarized Greek astronomy in a 13-volume work published in 141 A.D.

  23. Ptolemaic System:Ptolemy proposed a motionless earth at the center of our solar system (Geocentric) and people supported this for 13 centuries!

  24. Ptolemy’s Geocentric Model could not explain Retrograde Motion

  25. Retrograde Motion

  26. Retrograde motion is when the planet appears to stop, reverse its direction for a time and then resume the initial, eastward motion. • Retrograde motion cannot be possible, can it? Why? Then HOW does it exist?

  27. Retrograde Motion

  28. Modern Astronomy! “Modern” Astronomy uses natural laws as opposed to philosophical or religious views to determine astronomical theories.

  29. The Scientists involved in the modern Astronomical theory were from a variety of European countries.

  30. Nicolaus Copernicus (Poland)(1473-1543)

  31. Copernicus’ Conclusions • Determined that the earth is a planet, just like other five known planets, and that it rotates. • Also proposed a heliocentric solar system with circular orbits for the planets.

  32. Tycho Brahe (Denmark) aka Walrus Man(1546-1601)

  33. Became interested in astronomy while viewing astronomer-predicted solar eclipse. Persuaded King Frederick II to build observatory. Measured the locations of heavenly bodies for 20 years.

  34. Brahe made observations of Mars and made instruments with which to view the skies. This angle- measuring device was more precise than any previous methods.

  35. In the last year of his life, Brahe found an able assistant to continue his work: Johannes Kepler. Kepler would outshine his predecessor.

  36. Johannes Kepler (German)

  37. Brahe’ data did not make sense using a geocentric model. But when Keplerplaced the sun in the middle of the solar system, and suddenly the data made sense!

  38. Kepler’sLaws of Planetary Motion Kepler determined the laws of planetary motion. • Elliptical Orbits • Orbits sweep out equal areas in equal time intervals. • Square of period equals cube of distance.

  39. Kepler’sLaws of Planetary Motion Orbits sweep out equal areas in equal time intervals.

  40. Kepler’sLaws

  41. Kepler’s Third Laws of Motion…. • States that the square of the length of time that it takes a planet to orbit the sun (orbital period) is proportional to the cube of its mean distance to the sun. • Huh?

  42. In other words…. T2 d3 Comparing two planets:

  43. For the right units…. T2 = d3 Distance in astronomical units (1 AU = 150 million km = length of earth’s semi-major axis of its elliptical orbit around the sun) Period in Earth years.

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