1. Introduction to Astronomy

2. What is astronomy? Astronomy is the science that studies the universe. It includes the observation and interpretation of planets, stars, and other bodies in space. http://science.howstuffworks.com/telescope.htm Image credit: NASA / Apollo 8 crewmember Bill Anders.

3. Early astronomy (Those Ancient Greeks! Yes they were very smart. Observed the heavens, applied philosophy) Aristotle popularized the… Geocentric model of the universe: –Geo = __________ centr = __________ –Earth is the center of the universe; the sun and other plants revolve around it Aristotle (the guy in Carolina blue), as painted by Raphael

4. Why do the planets sometimes move backwards? Early astronomers observed: –planets move eastward against the background of stars. –Sometimes the planets seemed to stop, reverse direction, and then later carry on eastward. This apparent westward (backward) motion of the planets is called retrograde motion –Important! because it made them question the geocentric model Retrograde motion of Mars EastWest Sept. Aug. July June Dec.Jan.Feb.March April May (really puzzling)

6. Retrograde Motion Animation

7. Birth of modern astronomy Nicolaus Copernicus –Earth is a planet –proposed the… Heliocentric model of the solar system –Helio = __________ centr = __________ –Sun is the center of the solar system, planets revolve around it (including Earth) –better explained retrograde motion http://www.universetoday.com/33113/heliocentric-model/ Nicolaus Copernicus

8. Kepler’s Laws of Planetary Motion Kepler used Brahe’s observations to develop 3 laws to explain the movement of the planets – 1 st Law: Planets move in elliptical (oval) orbits around the sun – 2 nd Law: Planets move faster when they are closer to the sun

9. Planet revolution 1 st & 2 nd Law Animations

10. Kepler’s Laws of Planetary Motion Kepler used Brahe’s observations to develop 3 laws to explain the movement of the planets – 1 st Law: Planets move in elliptical (oval).orbits around the sun – 2 nd Law: Planets move faster when they are closer to the sun. – 3rd Law: The further the planet is from the sun, the longer its orbital period (p 2 =a 3 ) orbital period is the time (in Earth years) it takes a planet to go once around the sun. 3 rd Law Animation

11. Galileo’s telescope Galileo improved on the “new” invention… the telescope Amazing discoveries in great detail Detailed records of the heavens http://news.nationalgeographic.com/news/2009/08/photogalleries/galileos-telescope-pictures-anniversary/

12. Sir Isaac Newton: one heavy dude Developed a formula to explain gravity, now called the law of universal gravitation –All objects with mass have a gravitational pull –The greater the mass of an object, the greater is its pull on other objects –The pull decreases with distance –Meaning for the planets? –Tennis ball demo Gravity

13. Gravity’s influence on orbits

14. Motions of Earth Rotation –The turning, or spinning, of a body on its axis –Responsible for our days and nights (why?) –One complete earth rotation (one noon to the next) is about _____ hours http://www.physicalgeography.net/fundamentals/6h.html

15. Motions of Earth Revolution –The motion of a body, such as a planet or moon, along a path around some point in space (in this case, the sun) –One complete earth revolution is about _____ days – Perihelion is the time in Jan when Earth is closest to the sun; aphelion is the time in July when Earth is farthest from the sun –Volunteer ? http://science-class.net/Notes/Notes_Seasons_7th.htm

16. Motions of Earth Precession –The change in the direction in which the axis of the Earth points –Earth’s “wobble” –One complete cycle occurs about every _____ years –In 13,000 years (half- way), Polaris will no longer be our “North Star.”; instead it will be the star Vega (and summer will be winter) http://www.dreamstime.com/royalty-free-stock-images-spinning-top-toy-image15214709 Volunteer?

17. Precession Animation

18. Why do we have seasons? Earth’s tilt on its axis, along with its revolution around the sun causes the seasons! – As Earth moves around the sun, the tilt changes the angle of light received from the sun –Light hitting at direct angle = summer –Light hitting at indirect angle = winter http://education.arm.gov/teacher-tools/lessons/reason Earth’s Seasons

19. Phases of the moon The moon revolves around Earth –One complete revolution is about _____ days The moon changes shape (phase) because of the changing amount of sunlight reflected off the moon –These changes occur monthly

20. Phases of the Moon YouTube Song Moon Phases Animation What is a blue moon? Phases of the Moon

21. Motions of the moon The moon’s period of rotation on its axis and its revolution around Earth are the same (about a month) SO… we always see the same side of the moon volunteer? Why We See The Same Side of The Moon

22. Eclipses Normally the moon orbits about 5 degrees off the earth-sun orbital plane At special times of the year, the earth, moon, and sun “line up” Solar eclipse: when the moon is directly between Earth and the sun, casting a shadow on part of Earth.

23. Solar Eclipse What phase is the moon in during a solar eclipse? … and what time of day?

24. Solar Eclipse Solar eclipse Eclipses For 2013

25. Eclipses Normally the moon orbits about 5 degrees off the earth-sun orbital plane At special times of the year, the earth, moon, and sun “line up” Solar eclipse: when the moon is directly between Earth and the sun, casting a shadow on part of Earth. Lunar eclipse: when Earth is directly between the moon and the sun, casting a shadow on the moon.

26. Lunar Eclipse Lunar eclipse What phase is the moon in during a lunar eclipse? …and what time of day?

27. Origin of the moon Most widely accepted theory… When the solar system was forming, a body the size of Mars hit Earth. The resulting debris was thrown into space, began orbiting around Earth, and eventually united to form the moon.

28. Origin of the moon

29. Why is the moon so important? The moon calms Earth’s tilt; controls our tides, and so much more! While watching the movie, describe at least 10 ways our Earth would be different if we had no moon (page 17 in your notebook) The Day the Moon Was Gone (YouTube) Pt.1: start @ 43.24 The Day the Moon Was Gone (Amazon) Pt.1: start @ 43.24

30. Your summary Discuss with your table partner about what you will write in your summary box –Should be 1-3 sentences giving the major points of the Intro Astronomy notes … then write your summary!