Howardites

The answer sheet for the worksheet How the Solar System formed. Each answer comes with the reason, so it can be used to mark or to go over the questions with the class.

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GCSE · Ages 14 to 16 (Years 10 and 11)Answer sheet for teachers

Answers: How the Solar System formed

  1. A: Ice let them grow big enough to pull in gasFurther out, ice was available, so these planets grew large enough for their gravity to collect huge amounts of gas.
  2. A: HeliumHydrogen nuclei fuse into helium, releasing the energy that keeps the Sun shining.
  3. A: Its collapse under gravityThe cloud heated up as it collapsed under gravity; fusion only started once the core was hot and dense enough.
  4. C: It had to become hot and dense enoughFusion begins only when the core is hot and dense enough for hydrogen nuclei to join.
  5. D: 66 million6.6 × 10⁷ = 66,000,000, which is 66 million years.
  6. True (Their parent asteroids never melted, so early grains survive)Melting destroys the original grains; chondrites come from asteroids that never melted, so their early solids are preserved.
  7. False: the right answer is The Sun and the asteroids formed from the same cloudMatching proportions of elements point to a shared origin: the Sun and the asteroids formed from the same cloud.
  8. Droplets that were once molten, formed in the disc (accept any answer with the same meaning)Chondrules are once-molten droplets that formed in the disc around the young Sun.
  9. Older stars, before the Sun existed (accept any answer with the same meaning)The heavier elements were made in earlier stars; the Sun could not have made them, because it did not yet exist.
  10. It is the age of CAIs, the first solids to form (accept any answer with the same meaning)CAIs were the first solids in the disc, so their age marks the start of the Solar System.

Task

Answers will vary. The task comes from the lesson: Draw a labelled flow diagram of the formation of the Solar System in five stages: nebula, collapse and disc, protostar, fusion begins, planets and asteroids. Under each stage, write one piece of evidence from meteorites or observations that supports it.

Look for work that uses the key words correctly and gives a reason for each point.

Howardites · teacher copy: keep it separate from the pupil worksheets