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Beyond Earth

A star, a planet, or the Moon?

The dots in the night sky all look the same. Are they?

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Three dots in the sky. They look the same.
Step 1 of 4
  1. Three dots in the sky. They look the same.
  2. One makes its own light. It is a star.
  3. One circles the Sun and reflects its light. A planet.
  4. One circles the Earth and reflects its light. The Moon.

The rule

No: they can be stars, planets or the Moon.

  • Star — makes its own light.
  • Planet — circles the Sun. A planet only reflects the Sun's light.
  • Moon — circles a planet. Our Moon circles Earth. The Moon only reflects the Sun's light.

To circle is to go round something. To reflect is to send light back.

A star's dot twinkles, so its light seems to shake. A planet's dot shines steadily.

Watch out!

The Sun is a star. It is far bigger than any planet. Other stars look tiny only because they are far away.

Jump to lesson

This track

  1. 0 Start here
  2. 1 A star, a planet, or the Moon?
  3. 2 The Moon does not change shape
  4. 3 Waxing and waning
  5. 4 The Sun is a star
  6. 5 Eight planets, eight real distances
  7. 6 The sky can tell you north
  8. 7 What a telescope really adds
  9. 8 The big picture
  10. 9 Track quiz

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