Doppler Effect
What happens to the pitch of a sound when the source is moving toward you?
The pitch/sound increases (frequency increases).
What does the Big Bang Theory describe?
The origin of the universe from a hot, dense state that expanded over time.
Who discovered that galaxies are moving away from us?
Edwin Hubble.
Which type of wave on the electromagnetic spectrum has the longest wavelength?
Microwaves
A police siren sounds higher when approaching and lower when moving away. What is this phenomenon called?
The Doppler Effect.
Approximately how old is the universe according to the Big Bang Theory?
About 13.7 or 13.8 billion years.
What does Hubble’s Law state about galaxies’ velocity and distance?
The farther away a galaxy is, the faster it is moving away.
Which type of wave on the electromagnetic spectrum has the highest frequency?
Ultraviolet
Explain why how the wavelength of sound waves change when an object approaches.
The motion of the source compresses the waves, decreasing wavelength.
What type of radiation is evidence for the Big Bang?
Cosmic Microwave Background Radiation.
What does the relationship of the Hubble graph (velocity vs. distance) represent?
Direct Relationship
Place these in order from lowest to highest energy: visible light, ultraviolet, infrared.
Infrared → Visible light → Ultraviolet.
How does the Doppler Effect apply to light waves from distant galaxies?
Light shifts toward the red or blue end of the spectrum depending on motion (redshift for moving away, blueshift for moving toward).
Explain what direction galaxies appear to be moving from us in all directions.
Space/universe itself is expanding, carrying galaxies with it.
A galaxy is moving away at 30,000 km/s. According to Hubble’s Law, what can we infer about its distance?
It must be very far away, since velocity increases with distance.
Explain the relationship between wavelength, frequency, and energy in the electromagnetic spectrum.
As wavelength decreases, frequency and energy increase. (Indirect Relationship)
A star’s light is observed to be redshifted. What does this tell us about its motion relative to Earth?
The star is moving away from Earth.
How does the Big Bang Theory explain the abundance of light elements such as hydrogen and helium?
They were formed during the first few minutes of the universe when it was hot enough
How does Hubble’s Law support the Big Bang Theory?
It shows that the universe is expanding at a rapid rate
Why can astronomers use the electromagnetic spectrum to study stars?
Because stars emit light wave radiation (electromagnetic waves) with a frequency and wavelength that determine its color, temperature, composition, and motion across many parts of the spectrum.