1. Astronomy…It’s far-out! Sun – Earth – Moon

2. How do we know about space How do we know about space ?

3. `Direct Observation Boldly go where no man has gone before…

4. How can we go there? manned missions probes satellites What are the costs and advantages of each? dangers, spinoffs, limitations…

5. Indirect Observation Information comes to us: Electromagnetic Radiation traveling at the speed of light

6. Tools of Astronomy Optical Telescopes - reflecting - refracting Non-Optical Telescopes - ex. radio

7. Optical Telescopes: Reflecting use mirrors to focus light

8. Optical Telescopes: Refracting use mirrors to focus light

9. Radio Telescope VLA interferometry Arecibo, PR in a sinkhole

10. Radio Telescope Advantages Can ‘see’ through clouds, and during day Can be linked by computers – interferometry – to simulate a much bigger telescope (as big as the diameter of the Earth!)

11. Why is looking at the sky time travel?

12. Speed of Light Light travels at 300,000 km/s 7 times around Earth in 1 second!

13. How far can light travel in a year? (300,000km/s)(60s/min)(60min/hr)(24hr/day)(365.26days/yr) = 9.5 x 10 12 km in one year!

14. Light Year -is the distance light can travel in a year -It is much easier to say 4.3 light years than 41,000,000,000,000 kilometers.

15. AU -Astronomical Unit -Is the average distance from Earth to Sun -Ex. “Mars is 1.5 AUs from the Sun.”

16. AU!

17. Some fun facts… The Moon – formed 4.5 billion years ago – planet-sized object collided with Proto-Earth.

18. The Moon… is 4 th largest moon in solar system has 1/6 gravity of Earth is ¼ diameter of Earth affects our tides

19. Seasons

20. Caused by –Tilt of the Earth- axis is tilted 23 ½ degrees –Revolution of Earth around Sun S. hemisphere opposite of N. hemisphere

21. Tropics: the maximum distance north or south that the Sun ‘travels’ in our sky Solstice (June 21) Equinoxes Solstice (Dec. 21)

22. Winter Solstice- N. hemisphere points away from Sun, direct rays strike Tropic of Capricorn, first day of winter, Dec. 21 or 22 Summer Solstice- N. hemisphere points toward Sun, direct rays strike Tropic of Cancer, first day of summer, June 21 or 22

23. Spring Equinox (Vernal equinox)- March 21 or 22, Sun’s direct rays strike equator, first day of spring, 12 hours daylight and 12 hours darkness all over Earth Fall Equinox (Autumnal equinox)- September 22 or 23, direct rays strike equator, first day of Fall

24. Seasons Animation - Click it: http://esminfo.prenhall.com/science/geoanimations/animations/01_EarthSun_E2.html http://esminfo.prenhall.com/science/geoanimations/animations/01_EarthSun_E2.html

25. Eclipses happen when Moon or Earth blocks the Sun

26. Lunar Eclipse Occurs at full moon Earth’s shadow falls on Moon, Moon is not visible Moon often appears red due to bending of light

27. Lunar Eclipse Geometry

28. Solar Eclipse Occurs at new moon Moon blocks our view of the Sun

29. Solar EclipseGeometry

30. Eclipse Types Total- view is completely blocked from umbra- dark part of shadow Partial- view is partly blocked from penumbra- light part of shadow

31. Tides Rise and fall of Earth’s waters due to gravitational pull of Sun and Moon Moon has greater effect since it’s closer 2 high tides and 2 low tides each day (in most places)

32. Spring Tides Spring tide- extra high/low tide when sun and moon pull together

33. Neap Tides Neap tide- not much difference in tides when sun and moon pull in opposite directions

34. Shape of orbit

35. Perihelion and Aphelion