Howardites

The answer sheet for the worksheet Asteroids: the parent bodies. 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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Start here: Explorer · Ages 10 and upAnswer sheet for teachers

Answers: Asteroids: the parent bodies

  1. C: A flat, spinning disc of gas and dust around the young SunAround the young Sun was a flattened, spinning disc of gas and dust, where the planets were built.
  2. A: It slowly drifts fragments into resonancesOver millions of years, the Yarkovsky push can drift a fragment into a resonance, which then sends it inwards.
  3. C: Only about 3 per cent of our Moon's massThe asteroid belt contains surprisingly little material: only about 3 per cent of the Moon's mass.
  4. C: EarthIn melted asteroids metal sank to a core with rock above it, just as happened on Earth.
  5. A: Jupiter's regular tugs in a resonanceRepeated small pushes at the same point model how a resonance gradually changes an asteroid's path.
  6. False: the right answer is Dust, pebbles, planetesimals, planetsDust stuck into pebbles, pebbles grew into planetesimals, and many planetesimals merged into planets.
  7. True (More than a hundred)Scientists estimate that known meteorites sample more than a hundred different parent bodies.
  8. Iron meteorites (accept any answer with the same meaning)Differentiated asteroids give iron meteorites from their metal cores.
  9. It sank to form a core (accept any answer with the same meaning)In melted asteroids the metal sank to make a core, with rock above it.
  10. Small tugs timed at the same point add up over time (accept any answer with the same meaning)Like well-timed pushes on a swing, regular small tugs build up and gradually change the orbit.

Task

Answers will vary. The task comes from the lesson: Roll a marble across a table and gently blow on it from the side at the same point each time it passes. Notice how small, repeated pushes can change its path a lot. This is a rough model of how resonances work.

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

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