1. Environmental Science

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

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

14.  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.

16. Famous Greek Astronomers

26. Aristarchus first proposed the heliocentric model, but no one believed him.

32.  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?

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

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

38.  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.

40. 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.

41. 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.

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

45. Kepler determined the laws of planetary motion. 1. Elliptical Orbits 2. Orbits sweep out equal areas in equal time intervals. 3. Square of period equals cube of distance.

46. Orbits sweep out equal areas in equal time intervals.

48.  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?

49. T 2 d 3

50. T 2 = d 3

51.  For example:  Mars has an orbital period of T = 1.88 years. The square of 1.88 is 3.54 (T 2 ). The cube root of 3.54 is 1.52. So the distance from Mars to the sun is 1.52 AU = 228 million km.  The AU stands for astronomical unit is the average distance between the earth and sun is about 150 million km.

54.  Jupiter’s four moons;  That planets are circular disks;  That Venus has phases like our moons;  That the surface of our moon is not smooth;  The Sun’s sunspots.

57.  Is a Scientific Law that every body in the universe attracts every other body.  This force of attraction is proportional to their masses and inversely proportional to the square of the distance between their centers of mass.

58.  This force (called gravity) decreases with the square of the distance (inversely proportional).  The larger the mass, the larger the gravitational pull (directly proportional).  The moon has a strong enough pull that it causes tides, but a satellite does not have a large enough pull to have a measurable effect on Earth.