Astronomy

1. Astronomy Earth’s Place in the Universe

2. Agree or Disagree? • ___ Kepler discovered that the path of each planet around the sun is an ellipse. • ___ The universe is made of galaxies, galaxies contain stars, stars may have planetary systems.

3. What is Astronomy? • The science that studies the universe that deals with • Properties of objects in space • Laws under which the universe operates

4. Famous Astronomers • The Ancient Greeks • Ptolemy • Copernicus • Brahe • Kepler • Galileo • Newton

5. Famous Astronomers • Ancient Greeks • Geocentric view (Earth centered) • 7 heavenly bodies (Sun, Moon, Mercury – Saturn) and stars • Aristachus – Heliocentric (Sun centered), retrograde motion • Ptolemy: 141 AD • Geocentric Model • Copernicus: 1473 – 1543 • Earth was a planet • Model of the Solar System – Sun centered - heliocentric

6. Famous Astronomers • Galileo: 1564 – 1642 • Telescope in 1609 • 4 moons of Jupiter • Sunspots • Brahe: 1546 – 1601 • Solar Eclipses • Stellar paralax – shift in star’s position • Geocentric universe • Newton: 1643 – 1727 • Law of Universal Gravitation (Gravity) • 3 Laws of Motion (Inertia, forces, action/reaction) • Supported Kepler • Father of calculus

7. Famous Astronomers • Kepler: 1571 – 1630 • 3 Laws • 1st law: The orbits of the planets are ellipses, with the Sun at one focus of the ellipse. • 2nd law: The line joining the planet to the Sun sweeps out equal areas in equal times as the planet travels around the ellipse. • 3rd law: The ratio of the squares of the revolutionary periods for two planets is equal to the ratio of the cubes of their semimajor axes.

8. History of the Universe • Big Bang theory • States that at one time, the entire universe was confined to a dense, hot, super-mass ball • About 13.7 billion years ago, a violent explosion occurred, hurling this material in all directions • Marks the beginning of the universe

9. Nebula Theory • Theory of how the bodies of our solar system evolved from an enormous rotating cloud called the solar nebula. • Made up of Hydrogen and Helium • Theory how the planets were formed 8

10. The Expanding Universe Theory • The Expanding Universe Theory, developed from the observed red shifts of celestial bodies, that the space between galaxies is expanding, so that they appear to recede from us at velocities that increase with their distance 9

11. Types of Galaxies • Spiral • Disk-shaped with concentration of stars in the center and “arms”extending from the center • Contain old and young stars • Ex) Milky Way Galaxy • Elliptical • Round to oval in shape • Contain old stars • Ex) giant diffuse galaxies -largest • Irregular • No definite shape • Composed of young stars • Ex) Large and Small Magellanic Clouds (closest neighbor galaxies)

12. Agree or Disagree? • ___ Kepler discovered that the path of each planet around the sun is an ellipse. • ___ The universe is made of galaxies, galaxies contain stars, stars may have planetary systems.

13. End of day one!

14. Agree or Disagree • Revolution is the motion of a body along a path around some point in space. • Rotation is the turning, or spinning, of a body on its axis. • Barycenter is the center of mass between celestial objects. • Nutation is the wobble movement observed in precession.

15. Agree or Disagree • Precession is a slow movement in rotation of a body on its axis. • Earth’s revolution results in day and night. • One Earth around rotation the sun is a year. • Seasons on Earth are due to the Earth’s rotation around the Sun. • Seasons of the Northern and Southern hemisphere are opposite.

16. Rotation • The turning or spinning of a body on its axis • Causes day and night • Two kinds of measurement • Mean Solar Day – time interval from one noon to the next (24 hours) • Sidereal Day – time it takes for Earth to make one complete rotation (360’) with respect to a star other than the sun (23 hours, 56 minutes, 4 seconds)

17. Revolution • Motion of a body along a path around some point in space. • Earth’s orbit is elliptical • Earth’s distance from the sun varies • Perihelion • Earth is closest to the sun • 147 million km away • Occurs on January 3rd • Aphelion • Earth is farthest from the sun • 152 million km away • Occurs on July 4th

18. Precession • slight movement, over a period of 26,000 years where Earth’s axis points in different directions • Points to two stars • Polaris • Vega • Currently pointing to Polaris • Doesn’t affect the seasons

19. Nutation and Barycenter • Nutation • oscillatory movement of the axis of a rotating body or a wobble • occurs about 18.6 years • Barycenter • the point between two objects where they balance each other • the center of mass where two or more celestial bodies orbit each other • Barycenter website with animation

20. Seasons are caused by the tilting of the earth on its axis • When the Earth is tilted towards the Sun – warmer seasons • When the Earth is tilted away from the Sun – cooler seasons

21. How would you describe the Earth’s shape and appearance? What affects its shape? 17

22. End of Day Two! 18

23. Agree or Disagree • Tides are only caused by the Sun’s magnetic pull.

24. What are Tides? • changes in elevation of the ocean surface • What causes Tides? • Gravitational forces of the moon and sun

25. Tidal Range • Vertical distance between the high and low tides. • Vary from place to place and week to week.

26. Spring Tides • Spring Tides • Occur during the new and full moons • All gravitational forces are added together • Extreme high and low tides • High tidal range

27. Neap Tides • Neap Tides • During the 1st and 3rd quarters of the Moon • Gravitational forces are offset • Tidal range is the smallest value

28. Tides • Tides occur 50 minutes later due to … • Rotation pattern of earth and moon. • This is known as a lunar day

29. Tidal Patterns • Diurnal (daily) • one high and one low tide each lunar day. Occurs at Pensacola, Fl. And the Gulf coast. • Semidiurnal (semi-daily) • 2 high and 2 low tides: each high and low tides are similar to the preceding high and low. Occurs in the Atlantic coast • Mixed • 2 high and 2 low tides each day. Each high and low tides are different from each other. Occurs on the west coast.

30. End of Day Three! 25

31. Agree or Disagree? • Electromagnetic radiation includes gamma rays, X-rays, ultraviolet light, visible light, infrared radiation, microwaves and radio waves. • Nuclear fission and fusion are the same thing. • Sunlight is used in the process of photosynthesis for plants and other autotrophs to make energy. • Any living thing could exist without sunlight.

32. Light • Electromagnetic radiation (spectrum) • Gamma rays - fastest • X-rays • UV rays • Visible spectrum (ROYGBIV) • Infrared waves • Radio waves – slowest • Electromagnetic Spectrum: The arrangement of these waves according to their wavelengths and frequencies

33. Light: Wave or Particle? • Wave: Found on Earth • Particle: Photons found in space

34. Spectroscopy • Study of the properties of light that depend on wavelength. • Visible white light passes through a prism producing the colors of the rainbow (ROYGBIV)

35. The Sun • Solar Interior or Core • The Sun produces energy by a process known as nuclear fusion • Convection currents occur here • Enough fuel to last another 5 billion years

36. Fusion and Fission • Fusion • Particles “Fuse” together to create energy • Found on the Sun and Stars • Fission • Particles split to create energy • Found in Nuclear Reactors splitting atoms to create energy

37. Energy from the Sun • Solar energy into chemical energy through photosynthesis • Plants use sunlight to produce sugar through the actions of the chlorophyll • Chemical Formula • 6H2O + 6CO2 ----> C6H12O6+ 6O2 30

38. How does the magnetic field protect us from harmful solar radiation rays?

39. End of Astronomy Unit! 32