Red-shift

Question 1

What does red shift tell us about the universe

Answer 1

• Planets and galaxies are continuosly moving away form us
• This shows that the universe is constantly expanding

Question 2

What is the absorption spectra?

Answer 2

• All of the visible light that is emitted by the sun and absorbed by the Earth

Question 3

Why does the absorption spectra have gaps in it?

Answer 3

• The suns atmosphere contains lots of different chemicals
• Some of these differet chemicals absorb some of the wavelengths, resulting in gaps in the spectrum

Question 4

How does red shift work?

Answer 4

• When we absorb light from different galaxies, their absorption spectrum contains the same gaps as our absorption spectrum however, these gaps have been shifted towards the red end of the spectrum
• This is becauase the faster the galaxy is moving away from us, the greater the amount by which the light has shifted to the red end

Question 5

Why do light waves get stretched in red shift?

Answer 5

• As galaxies move away form us, they don’t move through space, rather the space between us stretches
• This causes the light waves travelling from the galaxy to us to stretch and result in a red shift
• The faster the galaxy is travelling, the more the space stretches and therefore, the more the light is stretched

Question 6

The Big Bang theory

Answer 6

• The universe was tiny, dense and hot and containe all of the matter
• After a while, the universe exploded and started to expand
• The universe continues to expand to this day