Pearson Edexcel International GCSE Science Single Award 17: Physics: Astrophysics
Pearson Edexcel International GCSE Science Single Award 4SS0 notes on physics: astrophysics.
Topic 8 places the solar system inside the wider universe, explains orbits through gravity and follows the life cycle of a Sun-like star. These notes follow Pearson 4SS0 Issue 4. Orbital-speed equations, massive-star endings, spectra, redshift, expansion and Big Bang evidence belong to broader routes and are excluded.
Cosmic hierarchy
The universe contains billions of galaxies. A galaxy contains billions of stars, together with gas, dust and other matter. Our solar system is inside the Milky Way galaxy. The solar system contains the Sun, planets, moons, smaller bodies and human-made objects, but it is not itself a galaxy.
Keep the hierarchy clear:
planet or moon, then solar system, then galaxy, then universe
Statements about scale are approximate descriptions of structure, not claims that every galaxy contains exactly the same number of stars.
Gravitational field strength
Gravitational field strength is force per unit mass and is measured in newtons per kilogram. Weight is:
The value of
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