ThursdaySeptember 6, 2012

(The Study of Light; Doppler Shifts; Videos

HTUW: The Big Bang, Part 3)

The Launch PadThursday, 9/6/12

Can you name the seven basic colors of visible light from lowest to highest frequency?

ROY G. BIV

Announcements• Please remember that we will

have our next Quiz tomorrow.

Assignment Currently Open

Summative or

Formative?Date Issued Date Due Date Into

GradeSpeed Final Day

ESS Class Information Sheet F1 8/27 8/28

ESS Class Procedures and

ExpectationsF2 8/27 8/29

Quiz 1 S1 8/31 8/31 8/31 9/14

Lab - Hubble’s Law - the

Expanding Universe

F3 9/4 9/6

??

Recent Events in ScienceHubble Captures a Collection of Ancient Stars

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.

http://www.nasa.gov/mission_pages/hubble/science/ancient-stars.htmlRead all about

it!

How the Universe

Works: The Big Bang

Part 3 Gravity

Video

The Study of Light • 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

wavelengthmotions

directionlonger

shorterhigher

• 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 wavelengthLight appears redder

Movement toward “squeezes” the wavelengthShorter wavelengthLight shifted toward the blue

The Study of Light

The Electromagnetic Spectrum

Figure 23.2

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

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 __________.

redaway from

velocity

Edwin HubbleHubble’s Law

distance

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.

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 radiationhttp://www.astrosurf.com/luxorion/audiofiles-misc-natural.htm