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								What is the primary topic of the theory of relativity?									 | 
								It is a theory of gravity - the force of gravity comes from distortions of space time.									 | 
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								What is spacetime?									 | 
								4 dimensional combination of space and time that forms the 'fabric' of our universe.									 | 
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								What are the 3 possible geometries of spacetime?									 | 
								Flat; spherical; saddle-shaped									 | 
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								What is a Doppler Shift?									 | 
								A shift in wavelength caused by motion towards or away from us.									 | 
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								What do we learn from redshift & blueshift?									 | 
								Red shift = away from us; Blue shift = towards us									 | 
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								How does a stars rotation affect its spectral lines?									 | 
								Faster rotation = broader spectral lines									 | 
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								The expansion of universe stretches ______ _______.									 | 
								Light wavelengths									 | 
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								How do we measure the age of a star cluster?									 | 
								By looking at its main sequecence turn-off point.									 | 
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								What happens when a star can no longer fuse hydrogen and helium into it's core?									 | 
								The core shrinks and heats up.									 | 
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								What happens if a star's helium core starts to shrink?									 | 
								Hydrogen fuses in a shell around the core.									 | 
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								What are the life stages of a low mass star?									 | 
								
	1. fuses hydrogen in it's core
	2. becomes red giant with hydrogen shell & helium insides									 | 
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								How does a low mass star die?									 | 
								It sheds it's outer layers and leaves a white dwarf.									 | 
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								A high mass star lives a (longer/shorter) life than a low mass star.									 | 
								Shorter									 | 
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								What are the life stages of a high mass star?									 | 
								
	1. fuses hydrogen into helium
	2. becomes a hydrogen shell
	3. burns heavier elements; becomes supergiant									 | 
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								How do high mass stars make the elements necissary for life?									 | 
								
	During it's final stages, the core becomes hot enough to fuse carbon & other elements. 
	This produces a wide range of elements; including all those needed for life. 
	They are released into space when the star dies. 									 |