Our Solar SystemAQA GCSE Physics: Flashcards

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What are the main components of our Solar System?

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What are the main components of our Solar System?: One star (the Sun), eight planets, dwarf planets, and natural satellites (moons).
What galaxy is our Solar System part of?: The Milky Way.
What is a nebula?: A cloud of dust and gas in space from which stars form under gravitational attraction.
What force pulls a nebula together to form a star?: Gravitational attraction.
What happens when fusion reactions begin in a young star?: They release energy that pushes outward, eventually balancing the inward pull of gravity — reaching equilibrium.
What two effects are in equilibrium in a stable star?: Gravitational collapse (inward) and the outward push of energy released by fusion reactions.
What provides the force that keeps planets and satellites in circular orbits?: Gravity.
What is the difference between a natural satellite and an artificial satellite?: A natural satellite (moon) forms naturally and orbits a planet; an artificial satellite is human-made and placed in orbit (e.g. for communications).
(HT) In a stable circular orbit, does gravity change an object's speed or its velocity?: Its velocity (direction) — the speed stays constant because the force acts at right angles to the direction of travel.
(HT) What must happen to an orbit's radius if the orbiting object's speed changes?: The radius must change too, for the orbit to remain stable.
Why does a moon not fly off in a straight line?: Gravity continuously pulls it towards the planet, curving its path into an orbit.
What is a dwarf planet?: A body that orbits the Sun but has not cleared other objects from its orbital path, so is not classed as a full planet.