IGCSE Physics: Space Physics
Space physics is the newest topic on the Cambridge 0625 syllabus and often the most under-revised. The questions are short but unforgiving on terminology — "redshift", "galaxy", "cosmic microwave background" must be used correctly. Cover the script once and you have easy marks.
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Open voice practiceWhat you need to master
- 1The solar system: planets, moons, asteroids and comets.
- 2Gravitational force and circular orbits.
- 3Stellar life cycle: from nebula to white dwarf / neutron star / black hole.
- 4Galaxies and the structure of the Universe.
- 5Redshift of distant galaxies and Hubble's law.
- 6The Big Bang model and the cosmic microwave background.
Key formulas
v = Hd (Hubble's law)
F = GmM/r² (gravitational force)
Examiner tips
- •For orbits: "the planet's speed is constant but its velocity changes because direction changes, so it accelerates" — memorise this sentence.
- •Redshift = longer wavelength = moving away; greater redshift = faster recession = further away.
- •Always link the cosmic microwave background to the Big Bang explicitly.
Common mistakes to avoid
- •Saying the Sun "orbits" the galactic centre without mentioning gravity as the cause.
- •Claiming redshift proves the Big Bang directly — it shows expansion; the CMB is the strongest Big Bang evidence.
- •Confusing the solar system with the galaxy.
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