Chapter 13 Flashcards
What unit is used to measure distances in the solar system?
Astronomical Units (AU)
Where does an AU come from?
The mean distance between the Earth and the Sun.
What unit is used to measure distances outside the solar system?
Light Year (ly) (Around 10^6m)
Where does a ly come from?
The distance that em waves travel through a vacuum in one year.
What are logarithmic scales used for?
Large ranges.
What diagram can be used to find the ages of stars?
The HR (Hertzsprung-Russell) diagram. It’s a plot of luminosity against temperature.
How can you work out the distance of a planet with a radar pulse? (Equation)
2d=ct (2d because the pulse travels there and back)
Explain the Doppler effect.
Waves “bunch up” in front of a moving object and stretch out behind it. The amount of stretching and bunching depends on the velocity of the source.
What happens when a light source moves away from us?
Redshift. The wavelengths of the light become longer and the frequency becomes lower. This shifts the light towards the red end of the spectrum.
What happens when a light source moves towards us?
Blueshift. The wavelengths of the light become shorter and the frequency becomes higher. This shifts the light towards the blue end of the spectrum.
What is the formula for the amount of red/blueshift?
Δλ/λ=v/c
When does time dilation happen?
When v is close to the speed of light.
Give evidence for the hot big bang theory.`
Redshift shows that galaxies that are further away are travelling faster, suggesting that everything started at a similar point.
CMBR-The electromagnetic radiation from the start of the universe has stretched into microwave radiation.
