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Keeping Time with the Skies

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You have seen the Moon change shape. Why does it? Where did the day, the month and the year come from?

A turn, a round of the Moon, and a trip round the Sun.

This is Chapter 11, Keeping Time with the Skies.

What you will learn

  • A day — the Earth spins once.
  • A shadow clock — a stick measures a day.
  • A month — the Moon's phases.
  • A year — the seasons come round.
  • A leftover — Moon months and years do not fit.
  • Leap years — a spare day in most fourth years.
  • Calendars — solar (Sun), lunar (Moon) and luni-solar (both).
  • Finding the Moon — where to look at sunset and sunrise.
  • Satellites — human-made objects that orbit (go round) the Earth.

Need a quick recap?

  • Something that repeats evenly (Time and Motion) — a clock counts repeats.
  • Two motions (Earth, Moon and the Sun) — spinning and going round.
  • The Moon (Beyond Earth) — it shines by sunlight.

Stay safe

Never look at the Sun, even through glasses or a lens. Watch its shadow instead.

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This track

  1. 0 Start here
  2. 1 Where a day came from
  3. 2 A shadow that tells the time
  4. 3 Where a month came from
  5. 4 Where a year came from
  6. 5 They do not divide
  7. 6 A spare day every few years
  8. 7 Calendars people use
  9. 8 Where to look for the Moon
  10. 9 Satellites above us
  11. 10 Checkpoint: the Moon in the sky and satellites
  12. 11 The big picture
  13. 12 Track quiz

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