Science 8 · Unit 6: Light · Cambridge Lower Secondary Science Stage 8

Questions

1. 1. What is the name of our galaxy?

   • the Solar System
   • the Sun
   • the Milky Way
   • Andromeda
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2. 2. What shape is the Milky Way?

   • a cube
   • a perfect sphere
   • a spiral
   • a straight line
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3. 3. What is the closest star to Earth?

   • Jupiter
   • the Sun
   • the Moon
   • Proxima Centauri
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4. 4. How many stars are in our galaxy?

   • between 100 and 1000
   • between 1000 and 1 000 000
   • more than 1 000 000
   • fewer than 100
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5. 5. What is a galaxy?

   • a huge group of stars, gas and dust held together by gravity
   • a single star
   • an asteroid belt
   • a planet and its moons
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6. 6. Is there gas and dust between the stars in our galaxy?

   • Only gas, never dust.
   • Yes, a small quantity.
   • No, it's completely empty.
   • Only around the Sun.
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7. 7. What word describes all of space and everything in it?

   • the Solar System
   • the atmosphere
   • the Universe
   • the galaxy
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8. 8. Why can we see other galaxies?

   • They reflect our Sun's light only.
   • They are very close.
   • They are made of mirrors.
   • Their stars give out light that reaches us.
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9. 9. What are the three shapes of galaxy?

   • hot, warm and cold
   • spiral, elliptical and irregular
   • big, medium and small
   • square, round and flat
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10. 10. Why don't scientists know exactly how many galaxies there are?

    • There are only ten.
    • There are too many to count, so they estimate.
    • Nobody has looked.
    • Galaxies are invisible.
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11. 11. How can tiny dust particles produce strong gravity in a galaxy?

    • Each particle is very heavy.
    • Dust repels stars.
    • Dust has no mass.
    • There are enormous numbers of them, giving a huge total mass.
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12. 12. What is the most common object in a galaxy that gives out its own light?

    • a planet
    • a moon
    • a star
    • an asteroid
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13. 13. Why do black holes appear black?

    • They are very cold.
    • Their gravity is so strong that light cannot escape.
    • They are holes with nothing.
    • They are painted black.
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14. 14. Most galaxies are moving apart. How will other galaxies look in the future?

    • smaller and fainter
    • closer together
    • exactly the same
    • bigger and brighter
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15. 15. How is estimating sand grains on a beach like estimating galaxies?

    • Guess without counting.
    • Count every single grain.
    • Weigh the whole beach.
    • Count a small sample and multiply up to the whole area.
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16. 16. Why does the Milky Way look like a milky band across the night sky?

    • It is a cloud in the atmosphere.
    • It is the edge of the universe.
    • We live inside a spiral galaxy and see one arm of it.
    • It is light reflected from the Moon.
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17. 17. What are galaxies made from?

    • only gas and dust
    • stellar dust, gas, stars and solar systems
    • planets and moons only
    • only stars
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18. 18. How did scientists estimate there are about 100 000 000 000 galaxies?

    • They counted every galaxy.
    • They guessed.
    • They looked them up in a book.
    • They counted the galaxies in one part of space and multiplied up.
    Check