COSMIC MICROWAVE BACKGROUND (CMB) RADIATION
3 marks · EasyThe universe is thought to have begun with a huge explosion called the Big Bang.
State one observation from distant galaxies that supports the idea that the universe is expanding.
Describe what the cosmic microwave background (CMB) radiation is.
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(a) Light from distant galaxies is red-shifted.
(b) CMB is faint microwave radiation detected from all directions in space, considered the afterglow of the Big Bang. · must show faint microwave radiation, detected in all directions, afterglow of the Big Bang (or released soon after)
Common mistakes: Describing CMB radiation as visible light; Not referencing expansion in red-shift evidence
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Marking points
B1 (a) · 1 mark · States an observation from galaxies supporting expansion, e.g. 'red-shift in light from distant galaxies'.
B1 (b) · 1 mark · States CMB is microwave radiation found throughout the universe.
B1 (b) · 1 mark · States it is detected in all directions or describes it as the afterglow of the Big Bang.
Worked solution
a) Light from distant galaxies is red-shifted, showing they are moving away from us.
b) The cosmic microwave background (CMB) radiation is faint microwave radiation detected in all directions in space—it's the afterglow left over from the Big Bang.