red shift

• What does the video explain that redshift provides evidence for?

  The Big Bang Theory
• What is the solar system part of?

  The Milky Way galaxy
• According to the video, how many galaxies does the universe contain?

  Hundreds of billions
• In what century were astronomers looking at the light emitted from different galaxies?

  The 1900s
• What did astronomers detect about the light from very distant galaxies?

  Increased wavelength compared to closer galaxies
• What happens when you pass light from the Sun through a prism?

  You get a spectrum
• What causes the dark lines in the solar spectrum?

  Elements in the Sun absorb specific wavelengths
• What is the term scientists use for the shift of lines towards the red end of the spectrum?

  Redshift
• What does redshift tell us about galaxies?

  Galaxies are moving away from each other
• Why does the movement of galaxies cause redshift?

  Light waves are stretched
• How does the redshift of distant galaxies compare to that of closer galaxies?

  Distant galaxies have a bigger redshift
• What does the larger redshift of distant galaxies indicate about their movement?

  They are moving faster
• What evidence does the video state supports the expanding universe?

  Distant galaxies moving faster than nearby galaxies
• What do scientists call the theory of the universe's origin?

  The Big Bang Theory
• According to scientists, how did the universe begin?

  From a small, hot, and dense region
• What did astronomers initially assume would happen to the expansion of the universe?

  It would gradually slow down
• What did observations of supernovas reveal about the expansion of the universe?

  The rate of expansion is increasing
• What have scientists suggested to explain the accelerating expansion of the universe?

  Dark matter and dark energy
• What two things have scientists suggested make up matter and energy that cannot be detected?

  Dark matter and dark energy