See if you can determine what the following magnified photos are.

Number your paper to 5.

The Answers:

Ch. 1 Section 3 pages 18-20

Measuring Distance in Space

Stars are much farther away than the planets are.

Astronomers use a special unit of length to measure these distances: light years.

A light year is a unit of length equal to the distance that light travels in one year.

One light year is equal to about 9.46 trillion kilometers.

Doppler Effect

A relative change in the frequency of a wave as the distance between the source and the observer changes.

We experience the Doppler Effect in two basic ways.

Red Shift = Moving away – There is a displacement in the spectral lines toward the red end indicating the source and the observers are moving away from one another. ( Longer wavelengths)

Blue Shift = Moving toward – There is a displacement in the spectral lines toward the blue end indicating the source and the observer are moving toward each other. (Shorter wavelengths)

Hubble discovered that the universe is expanding.

Therefore the universe shows evidence of red shift.

Blue Shift

Red Shift

No change

No change

1. How can you estimate the speed of a car that has

passed you just by listening to the pitch of its whine?

The greater the difference in the pitch above or below the normal pitch, the faster the car is moving.

2. Label the diagram below and tell if the observer perceives the pitch that is higher, lower, or just the same as the pitch heard by the driver.

A – lower B – the same C - higher

3. How does the Doppler shift affect the color of a star?

Stars moving toward us become slightly bluer.

Stars moving away from us become slightly redder.