The Solar System & Lifecycles of StarsEdexcel GCSE Physics: Flashcards

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What does our Solar System consist of?

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What does our Solar System consist of?: The Sun, eight planets and their natural satellites, dwarf planets, asteroids and comets.
Name the eight planets in order from the Sun.: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune.
For a body in circular orbit, what provides the centripetal force?: Gravity, directed towards the centre of the orbit.
Why does an orbiting planet have changing velocity but constant speed?: Velocity is a vector, so its direction continually changes even though the magnitude (speed) stays the same.
Why does weight differ on the Moon compared with Earth?: Gravitational field strength (g) is different on the Moon because it depends on the mass and radius of the body, so the same mass has a different weight.
What happens to orbital radius if a body's orbital speed changes (for a stable orbit)?: The radius must also change to keep the orbit stable.
List the life cycle stages of a star like the Sun.: Nebula → main sequence star → red giant → white dwarf.
List the life cycle stages of a star much more massive than the Sun.: Nebula → main sequence star → red supergiant → supernova → neutron star or black hole.
What balance controls a star's stability during the main sequence?: The balance between gravity pulling matter inwards and thermal expansion (from fusion) pushing matter outwards.
What is a nebula?: A cloud of dust and gas that can collapse under gravity to form a star.
What remains after a very massive star undergoes a supernova?: A neutron star, or a black hole if the remaining mass is large enough.
Why are some telescopes located outside the Earth's atmosphere?: Because the atmosphere absorbs or distorts many wavelengths of radiation (e.g. X-rays, UV, infrared) before they reach the ground.
How has our model of the Solar System's structure changed over time?: From an early geocentric model (Earth at the centre) to the modern heliocentric model (Sun at the centre, with planets orbiting it).