Scientific Theories about the structure of the Universe

1. Scientific Theories about the structure of the Universe Galaxies galore image from the Hubble Telescope http://imgsrc.hubblesite.org/hu/db/images/hs-2004-07-h-web.jpg

2. Planetary movement • Rotation: Planets spin on an axis • Revolution: Planets revolve around the sun http://tbn0.google.com/images?q=tbn:xE2IgogeAvHHIM:http://www.physicalgeography.net/fundamentals/images/earth_rotation.jpg http://www.uwm.edu/%7Ekahl/CoVis/Seasons/earth_revolution.jpg

3. Geocentric Modelof the Solar System • The Earth is stationary while the sky revolved above it on a set of celestial spheres. Today we know this is WRONG! http://wind.cc.whecn.edu/%7Emarquard/astronomy/images/ptolemaic.jpg

4. Copernicus’ Heliocentric Modelof the Solar System • The Sun is the center of the universe • The Earth, stars, and planets all revolved about the Sun. • Idea published by polish Nicolaus Copernicus (1473-1543) http:// http://tbn3.google.com/images?q=tbn:0wp3beLlcNY3VM:http://www.bbc.co.uk/blogs/ni/Copernicus.jpg www.conservapedia.com/images/thumb/0/0e/Copernicus_system.gif/300px-Copernicus_system.gif

5. Tycho Brahe 1546-1601 • Age 13 saw a partial solar eclipse; age 25 discovered a “very bright star” where none had been • No telescope - he built a large sextant. • 20 years of very precise data (accurate to 1 arc angle instead of 10) • Data passed on to Kepler

6. Kepler’s Laws of Planetary Motion • Johannes Kepler German mathematician, 1619, who proved that the planets travel in elliptical orbits around the sun. http://www.visualstatistics.net/East-West/Long%20Waves%20of%20Time/KeplerB.jpg

7. 1st law of elliptical orbits • The orbits of the planets are ellipses, with the Sun at one focus of the ellipse.

8. 2nd Law of Equal Areas • The line joining the planet to the Sun sweeps out equal areas in equal times • Planets are sometimes closer to the sun and sometimes further from the sun • When a planet is closer to the sun it moves faster when it is farther it moves slower.  Illustrating Kepler's 2nd law: segments AB and CD take equal times to cover.

9. 3rd Law of Harmonies • The farther a planet is from the sun, the longer its period of revolution. • Mathematical Equation: • T 2 = R 3 • The square of the time of one orbital period (T2) is equal to the cube of its average orbital radius (R3).

10. Background for Telescope Homework Galileo and the 1st telescope • In Galileo's version, light entering the far end (1) passed through a convex lens • (2), which bent the light rays until they came into focus at the focal point (f). • The eyepiece (3) then spread out (magnified) the light so that it covered a large portion the viewer's retina and thus made the image appear larger. Website with animation: http://www.pbs.org/wgbh/nova/galileo/telescope.html

11. Background for Telescope Homework "If I have seen further it is by standing upon the shoulders of giants."Sir Isaac Newton • In Newton's version, light streaming in one end (1) reflected off a concave mirror fixed inside the other end • (2), then off a flat mirror set an angle (3). • The light came into focus at the focal point (f) and then was magnified for the viewer by the eyepiece (4). http://www.pbs.org/wgbh/nova/galileo/telescope.html

12. Background for Telescope Homework 1925 Edwin Hubble • 1925 Edwin Hubble discovered there are galaxies beyond our Milky Way Galaxy http://www.nasa.gov/images/content/115745main_k_milkyway.jpg

13. Background for Telescope Homework Hale Reflecting Telescope on Palomar Mountain in California http://www.redorbit.com/modules/reflib/article_images/2_301ef105658994f337b5c9d724bd880d.jpg http://tbn2.google.com/images?q=tbn:1lRSmpI7nWuKnM:http://hpwren.ucsd.edu/images/20070804.jpg

14. Background for Telescope Homework Keck Multiple Mirror Telescope, Hawaii http://cass.ucsd.edu/public/tutorial/images/telescopes/keck_primary.jpg

15. Background for Telescope Homework Radio Telescopes: The Very Large Array in New Mexico

16. Background for Telescope Homework Radio telescope in Arecibo, Puerto Rico http://www.popsci.com/files/imagecache/article_image_large/files/articles/arecibo.jpg

17. Background for Telescope Homework Hubble Space Telescope http://www.rlrouse.com/astronomy/hubble-space-telescope.jpg http://startswithabang.com/wp-content/uploads/2008/09/hst2.jpg

18. The position of stars changes as the Earth Rotates around its axis • Time lapse photography of the night sky • Constellations are shapes people imagined stars made if they were connected by an imaginary line. They make using the stars as a “map” easier. http://www.world-mysteries.com/alignments/rotatingstars.jpg http://tbn1.google.com/images?q=tbn:zIQ52B42ZY6P5M:http://my.execpc.com/60/B3/culp/astronomy/fig/BigDipper.gif

19. Star Chart

21. The movement of planets vs. stars • Planets and stars both look like points of light in the night sky • The position of the stars relative to each other doesn’t change. • The planets move independently and faster then the stars across the night sky. http://tbn2.google.com/images?q=tbn:wS9GO5BqWs9MsM:http://www.physics.csbsju.edu/astro/CS/images/stars.N.1.b.gif

22. The ecliptic • the ecliptic is the plane of the Earth's orbit around the Sun. All planets and the sun move in their orbits on this plane. Notice Pluto is not very well aligned with the ecliptic plane of the other planets.

24. Retrograde Motion What is it? • Usually from Earth you can see the planets move from eastward against the background of constellations • Periodically planets will appear to move backward (westward) for a few weeks then it will start moving eastward again. This loop is called retrograde motion.

25. Retrograde motionWhy does it happen? • The “loops” that we see planets take are because each planet travels around the sun at a different speed. • When the Earth passes another planet, the planet appears to move backward.

26. Computer simulations Retrograde motion • http://www.lasalle.edu/~smithsc/Astronomy/retrograd.html • http://web.clas.ufl.edu/users/rhatch/pages/03-Sci-Rev/SCI-REV-Home/resource-ref-read/chief-systems/08-0retro-1.htm • http://mars.jpl.nasa.gov/allabout/nightsky/nightsky04-2003animation.html • http://www.astro.utoronto.ca/~zhu/ast210/helicentric.html

27. Lunar Phases • Website for simulation http://www.astro.illinois.edu/projects/data/MoonPhases/index.html

28. What causes the seasons? • Let's get rid of some common misconceptions about the seasons. The Earth's orbit is in the shape of an ellipse, so that sometimes the Earth is a little bit closer to the Sun than at other times. Is this the cause of the seasons? You can imagine that if the seasons were caused by the Earth's orbit, people in the northern hemisphere and people in the southern hemisphere would have the same seasons. For example, if winter occured because the Earth was far away from the Sun, everyplace on the Earth would be cold at the same time. • But this is not what happens! Summer in the northern hemisphere occurs at the same time as winter in the south, and vice-versa. It turns out that the Earth's orbit is nearly perfectly circular, and the difference between its closest point and its furthest point is very small. In fact, the Earth is furthest away from the Sun in June when it is summer in the northern hemisphere. • The Earth is a very special planet in many ways. Just as Earth's unique atmosphere and its distance from the Sun work together to make Earth the right temperature to support life, Earth's orbit and its rotation work together to create the seasons.

29. Website to explain seasons: http://www.windows.ucar.edu/tour/link=/the_universe/uts/seasons1.html&edu=mid&back=/search/search_navigation.html http://www.windows.ucar.edu/tour/link=/the_universe/uts/seasons2.html

30. Difference between seasons N S hemisphere photo • http://www.windows.ucar.edu/tour/link=/the_universe/uts/seasons3.html