Thursday September 6, 2012

1. ThursdaySeptember 6, 2012 (The Study of Light; Doppler Shifts; Videos HTUW: The Big Bang, Part 3)

2. The Launch Pad Thursday, 9/6/12 Can you name the seven basic colors of visible light from lowest to highest frequency? ROY G. BIV

3. Announcements • Please remember that we will have our next Quiz tomorrow.

5. Recent Events in Science Hubble Captures a Collection of Ancient Stars ?? Read all about it! http://www.nasa.gov/mission_pages/hubble/science/ancient-stars.html The NASA/ESA Hubble Space Telescope has produced this beautiful image of the globular cluster Messier 56 (also known as M 56 or NGC 6779), which is located about 33,000 light years away from the Earth in the constellation of Lyra (The Lyre). The cluster is composed of a large number of stars, tightly bound to each other by gravity.

6. Video How the Universe Works: The Big Bang Part 3 Gravity

7. The Study of Light • wavelength • The Doppler Effect is the apparent change in __________ of waves caused by the relative _______ of the source and observer. It is used to determine: • ________ of motion. • increasing distance – wavelength is ________ (“stretches.”) • decreasing distance – makes wavelength ________ (“compresses.”) • velocity – larger Doppler shifts indicate ______ velocities. http://www.youtube.com/watch?v=Kg9F5pN5tlI • motions • direction • longer • shorter • higher

8. The Study of Light • So, the Doppler Effect is the change in the wavelength of light emitted by an object due to its motion. • Movement away stretches the wavelength • Longer wavelength • Light appears redder • Movement toward “squeezes” the wavelength • Shorter wavelength • Light shifted toward the blue

9. The Electromagnetic Spectrum Figure 23.2

10. Doppler Shifts The amount of the Doppler shift indicates the _____ of movement . … a large Doppler shift indicates a ________ velocity … a small Doppler shift indicates a ________ velocity rate greater lesser

11. Doppler Shifts The Expanding Universe Most galaxies exhibit a ____ Doppler shift, meaning they are moving ___________ us. Far-away galaxies exhibit the greatest shift, therefore the greater __________. This phenomenon was discovered in 1929 by _________________. “_____________” states that the recessional speed of galaxies is proportional to their __________. red away from velocity EdwinHubble Hubble’sLaw distance

12. Doppler Shifts If a star (or galaxy) is stationary relative to us here on Earth, the light waves it emits are neither bunched together nor stretched out; therefore, it appears yellow. If a star or galaxy is approaching us rapidly, its light waves will be bunched together; therefore, it appears blue. If a star or galaxy is receding from us rapidly, its light waves will be stretched out; therefore, it appears red. Please note at this point that there are other factors that influence the color of a star. We will discuss this at a later date.

13. Question: Name two compelling pieces of evidence that support the Big Bang Theory? In 1929, astronomer Edwin Hubble discovered that most galaxies are moving away from one another. Hubble’s discovery indicated that the Universe is expanding in all directions. Diffuse cosmic background radiation http://www.astrosurf.com/luxorion/audiofiles-misc-natural.htm