Solar system; stability of orbital motions; satellites

When applying this idea, Solar system; stability of orbital motions; satellites sits inside 4.8 Space physics and should be revised as a connected set of physical ideas, not as isolated definitions. Context: the topic brings together Our Solar System, The life cycle of a star, Orbital motion, natural and artificial satellites and asks students to move between description, calculation, graph interpretation and explanation where appropriate. Key Concept: identify the quantity, model or interaction first, then state how evidence or a mathematical relationship supports it. Worked Example: for a typical exam item, name the relevant principle, use the given data or diagram, and finish with a sentence that interprets the physical consequence. Exam Focus: keep command words visible; describe asks for features, explain asks for a causal link, calculate requires equation, substitution and unit, and evaluate needs evidence. Common Mistake: avoid using a nearby concept as a substitute, such as confusing field with force, current with potential difference, speed with acceleration, or red-shift evidence with the Big Bang model itself.