The Universe Flashcards
What is used to help identify elements present in stars?
Line spectra
What happens when a substance is very hot?
It emits light
How can light be viewed?
Through a diffraction grafting as a continuous spectrum.
What do hot gases not emit?
A whole spectrum, only specific frequencies or wavelengths
What will a hot gas cloud release?
An emission spectrum comprising a series of light frequencies leaving a “chemical fingerprint”
What happens when a gas cools?
It absorbs the same frequencies of light that it would emit if hot.
What would happen if a continuous spectrum of light is passed through a gas cloud?
Absorbed frequencies appear as dark lines as they are ‘taken in’ by the gas cloud.
What is the doppler effect?
The wavelength of the emission will be compressed or extended depending on whether the source is moving towards or away from the listener.
What happens if a car is moving towards you?
The waves will be squashes together so wavelength is reduced. Therefore the pitch heard will be higher.
What happens if a car is moving away from you?
The waves will be stretched so wavelength is increased. Therefore the pitch heard will be lower.
What is red shift?
As the planet moves away from the observer the light wavelength is stretched so the light changes to be closer to the red end of the spectrum.
What is blue shift?
As the planet moves towards the observer the light wavelength is compressed so the light changes to be closer to the blue end of the spectrum.
What is cosmological red shift?
Galaxies must be moving away from the milky way and so hubble concluded that this cosmological redshift was caused by an increasing distance between galaxies suggesting there is an expanding universe.
What is Hubbles law?
“The increase in redshift is proportional to the distance away from Earth”
What is CMBR?
Cosmic microwave background radiation
