P16.4 The expanding universe

Question 1

What is a galaxy?

Answer 1

An enormous collection of stars that stay together because of the force of gravity between them.

Question 2

What is red - shift?

Answer 2

The light waves are stretched out if the star or galaxy is moving away from you.
The wavelength increases
This is red - shift because the spectrum of light is shifted towards the red part of the spectrum

Question 3

What is a blue - shift?

Answer 3

The light waves are squashed together if the star or galaxy is moving towards you. The wavelength of the waves is reduced
This is called a blue - shift because the spectrum of light is shifted towards the blue part of the spectrum

Question 4

What does a bigger shift mean?

Answer 4

The faster a star or galaxy is moving ( relative to you) the bigger the shit is