BRAINCAKE

Astronomy

Edexcel GCSE PhysicsTopic 7 of 1519 lessons

Revision notes for Astronomy in Edexcel Physics (1PH0). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. Weight and g on Earth, the Moon and other bodiesThe weight of an object is the force of gravity pulling on it.
  2. The Solar SystemOur Solar System is held together by the gravity of the Sun, which is a star at its centre.
  3. The eight planets in orderThe eight planets, in order of distance from the Sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
  4. How ideas about the Solar System have changedEarly astronomers believed in the geocentric model, with the Earth at the centre and the Sun, Moon, planets and stars all moving round it.
  5. Orbits of moons, planets, comets and artificial satellitesAn orbit is the path of one body round a larger one, held in place by gravity.
  6. Gravity, circular orbits and changing velocitySpeed only tells you how fast something moves.
  7. Orbital speed and orbital radiusA satellite or planet stays in a stable orbit because gravity pulls it towards the body it orbits and keeps changing the direction of its motion.
  8. Steady State and Big Bang theoriesScientists have proposed two main theories for the origin of the Universe.
  9. Evidence for the Big Bang theoryTwo pieces of evidence support the Big Bang theory: the red-shift of light from galaxies and the cosmic microwave background (CMB) radiation.
  10. The accepted model for the origin of the UniverseScientists accept a theory when the evidence supports it and it explains what we observe.
  11. Wave sources moving relative to an observerIf a wave source and an observer are not moving relative to each other, the observer receives waves with the same frequency and wavelength that the…
  12. Red-shift and distance of galaxiesWhen astronomers split the light from a galaxy into a spectrum, they see dark lines at particular wavelengths.
  13. Red-shift and the expanding UniverseGalaxies are huge collections of stars.
  14. Big Bang and Steady State: explaining red-shiftTwo theories try to explain the origin of the Universe.
  15. The CMB and the accepted modelThe Big Bang theory predicts that the early Universe was extremely hot and full of very high energy radiation.
  16. Life cycle of a star like the SunStars form from a nebula, a huge cloud of dust and gas that is mostly hydrogen.
  17. Gravity and thermal expansion in starsInside a star two effects compete.
  18. Life cycle of a massive starA star with a mass much larger than the Sun starts in the same way, as a nebula that gravity pulls together into a main sequence star.
  19. How methods of observing the Universe have changedFor most of history, people studied the sky with the naked eye alone.

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