Space Flashcards
What is the geocentric model of the universe?
A model which places the earth at the center of the universe
What is the Big Bang theory?
The theory that to begin with all the mateyr in the unjverse was concentrated into tiny single point and then rapidly began expanding.
What is the Doppler Effect?
When a source moves towards an observer, the observed wavelength decreases and frequency increases. When the source moves away, the observed wavelength increases and frequency decreases - when a car drives past it goes quiet and low then higher and louder and quieter and lower.
What is redshift?
Light shifts towards the red end of the spectrum as a source of light is moving away. Lightbwhich shows redshift means the source is moving away from us
What is Blueshift?
When a source of light is moving towards us, it shifts to the blue end of the light spectrum
How can we use absorption lines to detect elements in space?
If you pass light through a gas, some wavelengths of light will be absorbed by it. The colours that are absorbed are unique to different elements and we can chart these on a spectrum to know that e.g. our sun contains helium.
How does red-shift support the big bang theory?
Red shift suggests that everything in the universe is moving away from a single point.
How does Cosmic Microwave Background Radiation (CMBR) support the Big Bang Theory?
The Big Bang Theory predicted the presence of CMBR, relatively uniform background energy from the big bang.
How are stars made?
Gravity pulls clouds of gas and dust together ofver a very long time. If enough material is pulled together, it gets very hot and starts to shine - it is a star
What keeps a star stable?
The star’s mass tends to make it collapse which makes the core hot enough for nuclear fusion and then the energy released by the nuclear fusion produces a very high temperature which creates pressure than makes the star expand. Over a star’s life, these forces are equal and keep the star stable.
What causes a star to become a red giant?
Once most of the sun’s hydrogen has been converted into helium, it will expand into a red giant
What happends to stars up to 3 times the mass of the sun after they are red giants?
They become white dwarfs and gradually cool to brown dwarvfs
What happens to stars more than 3 times the mass of the sun?
They eventually become a suprenova explosion and then become a neutron star
