space 2 Flashcards
what does light from other galaxies under go
red shift
what is red shift
the frequency of the wave decreases but the wavelength increases
the spectrum of light is shifted towards the red part
what does red shift show
the galaxy is moving away from us
what does blue shift show
galaxy is moving towards us
how do we observe the shifts of light
by observing dark lines in the spectra from galaxies
what does the further away the galaxy mean
the greater the red shift
what are all the distant galaxies doing
moving away from eachother so the universe is expanding
what is the big bang theory
if the universe is now expanding outwards, this suggests it started with a massive explosion
what did scientists discover
-microwaves coming from every direction in space
-from the big bang
what are the microwaves called in which come from all directions in space
cosmic microwave background radiation
what does the fate of the universe depend on
the density of it
what is dark matter
the stars in the galaxy are only a small percentage of its mass
the rest is dark matter
what is the big yawn
if the density of the universe is less than a particular amount then it will expand forever
what is the big crunch
if the density of the universe is more than a particular amount it will stop expanding and go into reverse
