Download An Expanding Universe

An Expanding
Universe
Redshift, Blueshift and the
Doppler Effect
EMS Review
• The shorter the wavelength, the higher the
frequency
• The longer the wavelength, the lower the
frequency
• Red wavelengths of light are longer than blue
wavelengths of light
• Star composition can be determined by the
spectrum of the gases present
Doppler Waves
• As an object moves away from you, the waves
spread out. Wavelength gets longer and frequency
decreases.
• When dealing with light waves, we say that the
object has red-shifted because the waves move
towards the red end of the spectrum
Doppler Waves
• As an object moves towards you, the waves bunch
up. Wavelength gets shorter and frequency
increases
• We say that the object has blue-shifted because the
waves move towards the blue end of the spectrum.
How can we tell that the universe is
expanding?
As an object moves away from you, the
object’s spectrum of gases shifts to the red
side of the spectrum
Shifting Spectrums
Red shift/Blue shift Practice
Blue
Red
Nearby Star
Andromeda Galaxy
Bernard’s Galaxy
Bear Galaxy
Venus
SR - 5
Which galaxy
or planet is
moving at
the same
speed as the
nearby star?
Red shift/Blue shift Practice
Blue
Red
Nearby Star
Andromeda Galaxy
Bernard’s Galaxy
Bear Galaxy
Venus
SR - 5
What
galaxies or
planets are
moving
toward the
nearby star?
Red shift/Blue shift Practice
Blue
Red
Nearby Star
Andromeda Galaxy
Bernard’s Galaxy
Bear Galaxy
Venus
SR - 5
What
galaxies or
planets are
moving away
the nearby
star?
Red shift/Blue shift Practice
Blue
Red
Nearby Star
Andromeda Galaxy
Bernard’s Galaxy
Bear Galaxy
Venus
SR - 5
Is the
Andromeda
galaxy red or
blue shifted?
Red shift/Blue shift Practice
Blue
Red
Nearby Star
Andromeda Galaxy
Bernard’s Galaxy
Bear Galaxy
Venus
SR - 5
Which galaxy
or planet is
moving
fastest away
from the
nearby star?
Red shift/Blue shift Practice
Blue
Red
Nearby Star
Andromeda Galaxy
Bernard’s Galaxy
Bear Galaxy
Venus
SR - 5
Which galaxy
or planet is
moving the
slowest away
from the
nearby star?