QUESTION 1:
In 1929, the astronomer Edwin Hubble observed that the light from galaxies moving
away from the Earth had longer wavelengths than expected.
What name is given to this effect?
[1 mark]
a) From his observations, Hubble was able to calculate the speed of a galaxy and the
distance of the galaxy from the Earth.
b)What relationship between the speed of a galaxy and the distance is suggested by
Hubble’s results?
Answer
a) Name of the effect:
Redshift
Light from galaxies moving away is stretched to longer wavelengths, which appear redder than
normal.
b) Relationship between speed and distance:
The farther a galaxy is from Earth, the faster it is moving away.
This relationship is known as Hubble’s Law.
Expressed simply:
speed of galaxy = H0 × distance from Earth
where H0 is Hubble’s constant.
Note:
Hubble’s observations show a direct proportionality between speed and distance.
QUESTION 2:
Give one strength and one weakness of this model in representing the idea of an
expanding Universe.
[2 marks]
SOL:
a)strength:
The model clearly shows that galaxies move away from each other, which supports the idea
of an expanding Universe
, b)weakness:
The model cannot show the expansion of space itself; it only shows galaxies moving apart
in a simplified way.
QUESTION 3:
In the 1950s there were two main theories to explain how the Universe began.
Theory 1:
The Universe has always existed, it is continually expanding. New galaxies
are formed as older galaxies die out.
Theory 2:
The Universe began from a very small region that was extremely hot and
dense. The Universe has been expanding ever since.
PART a).
In what way do the observations made by Hubble support both Theory 1 and
Theory 2?
[1 mark]
Part b)
Most scientists now believe that Theory 2 is correct.
Suggest what is likely to have caused scientists to start thinking Theory 1 is wrong.
[1 mark]
Answer:
a) How Hubble’s observations support both theories:
Hubble observed that galaxies are moving away from each other, showing that the Universe is
expanding.
Expansion is consistent with both Theory 1 (Universe has always existed) and Theory 2
(Universe began from a small, dense region).
b) Why scientists now favor Theory 2 over Theory 1:
Observations such as the cosmic microwave background radiation and evidence of a hot, dense
early Universe indicate that the Universe had a beginning, which contradicts Theory 1.
In 1929, the astronomer Edwin Hubble observed that the light from galaxies moving
away from the Earth had longer wavelengths than expected.
What name is given to this effect?
[1 mark]
a) From his observations, Hubble was able to calculate the speed of a galaxy and the
distance of the galaxy from the Earth.
b)What relationship between the speed of a galaxy and the distance is suggested by
Hubble’s results?
Answer
a) Name of the effect:
Redshift
Light from galaxies moving away is stretched to longer wavelengths, which appear redder than
normal.
b) Relationship between speed and distance:
The farther a galaxy is from Earth, the faster it is moving away.
This relationship is known as Hubble’s Law.
Expressed simply:
speed of galaxy = H0 × distance from Earth
where H0 is Hubble’s constant.
Note:
Hubble’s observations show a direct proportionality between speed and distance.
QUESTION 2:
Give one strength and one weakness of this model in representing the idea of an
expanding Universe.
[2 marks]
SOL:
a)strength:
The model clearly shows that galaxies move away from each other, which supports the idea
of an expanding Universe
, b)weakness:
The model cannot show the expansion of space itself; it only shows galaxies moving apart
in a simplified way.
QUESTION 3:
In the 1950s there were two main theories to explain how the Universe began.
Theory 1:
The Universe has always existed, it is continually expanding. New galaxies
are formed as older galaxies die out.
Theory 2:
The Universe began from a very small region that was extremely hot and
dense. The Universe has been expanding ever since.
PART a).
In what way do the observations made by Hubble support both Theory 1 and
Theory 2?
[1 mark]
Part b)
Most scientists now believe that Theory 2 is correct.
Suggest what is likely to have caused scientists to start thinking Theory 1 is wrong.
[1 mark]
Answer:
a) How Hubble’s observations support both theories:
Hubble observed that galaxies are moving away from each other, showing that the Universe is
expanding.
Expansion is consistent with both Theory 1 (Universe has always existed) and Theory 2
(Universe began from a small, dense region).
b) Why scientists now favor Theory 2 over Theory 1:
Observations such as the cosmic microwave background radiation and evidence of a hot, dense
early Universe indicate that the Universe had a beginning, which contradicts Theory 1.
