Which galaxy contains the Solar System?
The Milky Way.
Cambridge IGCSE (9–1) Physics 0972 (Extended) (2026–2028) · 6.2.3
Revise Cambridge IGCSE (9–1) Physics 0972 (Extended) (2026–2028) specification point 6.2.3, The Universe, with free active-recall flashcards. Flip through the set or review every question and answer below.
1 / 10
Which galaxy contains the Solar System?
The Milky Way.
Approximately how many galaxies make up the Universe?
Many billions.
What is the approximate diameter of the Milky Way?
100,000 light-years.
What is a light-year?
The distance light travels in one year; it is a unit of distance, not time.
What is redshift for a source moving away from an observer?
An increase in the observed wavelength of its electromagnetic radiation.
How does light from distant galaxies compare with corresponding light emitted under the same conditions on Earth?
It is observed at longer wavelengths.
Must redshifted radiation appear red?
No. Redshift is a shift toward longer wavelengths, but the radiation does not have to appear red.
What does the redshift of light from distant galaxies indicate about their motion and the Universe?
The galaxies are moving away from us, indicating that the Universe is expanding.
Why does the expansion of the Universe support the Big Bang theory?
It implies that the Universe was smaller and denser in the past.
How does the Big Bang theory describe the development of the Universe?
The Universe developed from an early hot, dense state as space expanded.