Skip to content
Exit presentation

Earth, Moon, and the Sun

The Moon keeps one face turned to us

The Moon shows us the same markings every night. Nobody sees its far side from Earth.

Loading lab…

The idea

Earth in the middle. The Moon at one spot, marked side facing Earth.
Step 1 of 4
  1. Earth in the middle. The Moon at one spot, marked side facing Earth.
  2. The Moon moves a quarter of the way round.
  3. The marked spot still faces Earth.
  4. One turn on itself equals one trip round Earth.

The rule

The Moon turns once in each trip round Earth. So one face always points at us.

The far side is not dark. The far side gets sunlight too. We cannot see it from Earth.

Watch out!

The Moon does turn. If it did not turn, the far side would come into view.

Jump to lesson

This track

  1. 0 Start here
  2. 1 Earth is doing two things at once
  3. 2 The Moon keeps one face turned to us
  4. 3 When three line up, one shades another
  5. 4 The Moon shades a patch of Earth
  6. 5 Earth shades the Moon
  7. 6 Why it is not every month
  8. 7 One is safe to watch, the other never is
  9. 8 Checkpoint: motions, the Moon and eclipses
  10. 9 Why the Sun seems to move
  11. 10 Day here, night there
  12. 11 The star that stays still
  13. 12 Checkpoint: the turning sky
  14. 13 The night sky changes through the year
  15. 14 The tilt makes the seasons
  16. 15 The longest and shortest days
  17. 16 Checkpoint: the year, the tilt and the seasons
  18. 17 The big picture
  19. 18 Track quiz

Other tracks