Project ASTRO San Diego Scientists & Educators in Partnership for Learning

1. Project ASTRO San DiegoScientists & Educators in Partnership for Learning A national program (since 1993) created by the Astronomical Society of the Pacific Locally funded and organized: Site Director: Dr. Ron Angione Site Coordinator: Dr. Philip Blanco Lead Institution:San Diego State University …with a coalition of local organizations

2. Today’s Workshop: Galileoscope • Learn a little about optics • Assemble Galileoscope™ • Test telescope • Discuss how to use Galileoscopes in the classroom • Learn about local astronomy/space resources All slides, links to resources will be posted at http://mintaka.sdsu.edu/projectastro/galileoscope

3. LOCAL RESOURCES • SDAA: San Diego Astronomy Association: • “Star Party” at your school • Mars Society, San Diego Chapter • Classroom and school visits, public displays • AIAA: American Institute of Aeronautics & Astronautics • $200 Educator grant for materials, just by applying! • Palomar Observatory • Tours and public displays • Project ASTRO San Diego – always here to help! • Additional activities and useful links on our website • Loaner telescopes (Sunspotter, Coronado PST, solar white light, 90mm telescope)

4. Project ASTRO loaner telescopes • Sunspotter – projects Sun’s image in natural light • Coronado PST – “H-alpha” telescope for viewing prominences Also (not here today): • 90mm “H-alpha” telescope for viewing prominences • 90mm night sky telescope with motor drive

5. Optics: The Ray Model of Light Waves Light waves often travel in straight lines. We represent the wave direction using rays - an idealization, but useful

6. Reflection: Virtual Image Formed by Plane Mirror What you see when you look into a plane (flat) mirror is a virtual image, which appears to be behind the mirror – but cannot be projected on a screen

7. Refraction = bending of light When light waves enter water or glass, they slow down and change direction This what makes half-submerged objects look strange!

8. Thin Lenses: Lots of shapes, 2 types: Converging - bends light rays together - mostly convex shapes Diverging - spreads light rays apart - mostly concave shape

9. Converging lens: real focus • Parallel rays brought to a focus in front of lens • each point on distant object makes a sharp image on the focal plane • image can be projected on screen or captured on film

10. Diverging Lens focal point is behind the lens where diverging rays appear to come from – a virtual focus - can only see or project this image with another lens (e.g. human eye)

11. Optical instruments: The image formed by the first (objective) lens becomes the object for the second (eyepiece) lens

12. Keplerian (astronomical) telescope: Image formed by the objective lens now becomes the object for eyepiece lens

13. Galilean Telescope Used for viewing objects on Earth, produces upright image

14. Galileoscope objective lens: achromatic doublet” Different colors are separated in a single lens – using a second lens of a different glass type corrects this.

15. Light and Telescopes

16. 2 basic types of telescopes • refracting: uses glass lenses to concentrate incoming light • Reflecting: uses mirrors to concentrate incoming starlight

17. A refracting astronomical telescope uses 2 lenses to collect and concentrate light

18. Three main functions of a telescope Most important!! 1. Gather Light – make faint objects visible • depends on diameter of objective lens or mirror (e.g. “90mm”, “2.5 meter”) followed by: 2. Resolution - to separate objects and see fine detail • also depends on diameter of objective lens or mirror and least important, 3. Magnification of the image - depends on focal lengths of objective and eyepiece

19. A larger objective lens provides a brighter (not bigger) image

20. Angles Q. What is an “arcminute”? A. human eye cannot separate objects separated by less than ~1 arcmin. (~ separation of dots on a TV seen 6 feet away) Q. What is an “arcsecond”? ~ how much a star’s position changes when it twinkles… ~ dime seen from 2 km away…

21. Angular vs. actual size e.g. How do we “know” that the kids at top of picture are farther away? Different sizes, or different distances (or both!)?

22. Holding up a model at Legoland?…

23. …or standing in front of the real thing?

24. Which brother is taller? • Angular size increases with actual size, …but decreases with distance

25. Galileo: Father of Modern Science and Astronomy • Math professor in Pisa, Italy • First to examine the sky with a telescope • wanted to connect physics on earth with the heavens • Used scientific method to disprove Ptolemaic system • Dialogue Concerning the Two Chief World Systems[written in Italian] • Caused trouble with Catholic Church Galileo Galilei (1564-1642)

26. Galileo’s Telescopic Discoveries

27. saw shadows cast by mountains on the Moon observed craters Concluded: Moon has a landscape; it is a “place”, not a perfect heavenly body. Galileo’s Observations: Lunar Features

28. Galileo’s Observations: Sunspots! 2010 Aug 14 - www.spaceweather.com  Sun not a “perfect” body - and rotates on axis (~27 days) NEVER LOOK DIRECTLY AT THE SUN!

29. Sunspots are… …cooler than other parts of the Sun’s surface (4,000 K) …regions with strong magnetic fields

30. 11-year solar activity cycle: 2009-10 was a “solar minumum”

31. The sunspot cycle has something to do with the winding and twisting of the Sun’s magnetic field.

32. Magnetic activity also causes solar prominences that erupt high above the Sun’s surface.

33. Magnetic activity can also cause solar flares that send bursts of X-rays and charged particles (plasma) into space.

34. Coronal mass ejections send bursts of energetic charged particles out through the solar system.

35. Galileo’s Discoveries: Milky Way • “innumerable stars” • Amateur photo - Riverside, CA

36. discovered Jupiter has 4 moons Jupiter is at center of its own system.  Heavenly bodies exist which do not orbit Earth Galileo’s Observations: Jupiter’s Moons Amateur photo: can use Galileoscope or 1050 binoculars on tripod

37. Scientific Method revisited… 0. Observe Nature (specific cases) 1. Ask a Question (How/why…?) 2. Induce a general Hypothesis • i.e. an intelligent guess 3. Make specific predictions 4.Test predictions! 5. Report reproducible results 6. Confirm, reject, or modify hypothesis

38. Galileo’s observations: Phases of Venus Geocentric: -predicts only cresecent phases Heliocentric: all phases expected, with largest angular size at crescent phase (closest to Earth) Galileo realized that telescope observations would falsify one of these hypotheses!

39. Galileo’s observations: Phases of Venus Heliocentric: - predicts all phases, with largest angular size at crescent phase (closest to Earth) Geocentric: -predicts only crescent phases The data: All phases observed! Venus orbits Sun, not Earth Ptolemaic model falsified!

40. Galileo and his trouble with the Church Dialogue Concerning the Two Chief World Systems - Trial, house arrest until his death - removed from Banned Books list 1824 - pardoned by Pope John-Paul II in 1992 • Galileo’s finger, on display in Florence, Italy

41. Today’s Workshop: Galileoscope • Learn a little about optics • Assemble Galileoscope™ • Test telescope • Discuss how to use Galileoscopes in the classroom • Learn about local astronomy/space resources All slides, links to resources will be posted at http://mintaka.sdsu.edu/projectastro/galileoscope