space - red shift Flashcards
what did astronomers in 1900s, looking at the light emitted from different galaxies find out?
the light from distant galaxies has an increased wavelength compared to light from closer galaxies
why are there dark lights in the light spectrum from the sun?
certain elements in the Sun absorb light or specific wavelengths so those wavelengths appear as dark lines
what is the red shift?
when all the dark lines in the light spectrum shift towards the red end.
red shift tells us the galaxies are moving away from each other. because the galaxies are moving away, the light waves are stretched (observed wavelength are increased)
what galaxies have a bigger red shift?
those further away so these galaxies are moving faster than those that are closer
_______ galaxies have a _______ _________, showing us that they are _______ away.
_______ _______ galaxies have a ________ redshift. They are moving away _____
___ _______ galaxies have a _____ ______ redshift. They are moving away _____ _____
nearby, small, redshift, moving
more distant, larger, faster
Very distant, very large, very fast
what provides evidence that the universe is expanding?
the fact that distant galaxies are moving faster than nearby galaxies. scientists believe the universe started from a very small region that was extremely hot and dense. this region then expanded into the universe we know today (Big Bang theory)
what was noticed in 1988 and why was this strange?
scientists originally assumed that gravity would cause the expansion of the universe to gradually slow down however observations of supernovae show the rate of expansion is actually increasing. expanding faster rather than gradually slowing down. cannot explain this
what have scientists suggested in recent years for the reasons on the expansion of the universe?
universe contains matter and energy that we cannot detect. there are called dark matter and dark energy. this could explain why the rate of expansion is speeding up
