Geology

1. Where does everything on Earth ultimately come from?

   Solution

   Stars

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2. What may have triggered the formation of our sun and the planets?

   Solution

   The massive explosion of a long lost star

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3. About how many galaxies are there in the universe?

   Solution

   Uncountable billions

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4. How many stars are there in the Milky Way Galaxy?

   Solution

   Billions

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5. What is the name of the nearest star to our solar system?

   Hint

   ‘Proximatus’ is Latin for ‘approach’.

   Solution

   Proxima Centauri

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6. About how long would it take a fast jet to reach the nearest star to our solar system?

   Solution

   More than a million years

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7. How far is a light year?

   Solution

   The distance light travels in one year—about 9 trillion km

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8. How far across do scientists think the visible Universe is?

   Hint

   Best to count in light years, which is a measure of distance not years.

   Solution

   At least 93 billion light years

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9. What is the name of our home galaxy?

   Hint

   You can see it on a clear night.

   Solution

   The Milky Way

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10. What do scientists think is hiding at the center of our galaxy?

    Solution

    A super-massive black hole.

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11. What keeps the planets orbiting around the sun?

    Solution

    The gravitational pull of the sun

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12. What is a Goldilocks Zone?

    Hint

    What is absolutely essential for life on our planet?

    Solution

    An orbit that is just the right distance from the sun to support liquid water.

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13. Which are the four rocky planets?

    Hint

    They are the closest planets to the sun.

    Solution

    Mercury, Venus, Earth, and Mars

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14. What do scientist mean when they refer to "accretion" in space?

    Solution

    The slow process of planet building caused by star dust clumping together.

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15. What causes star dust to clump together?

    Solution

    The force of gravity

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16. How long ago do scientist think our solar system began to form?

    Solution

    About 4.6 billion years ago ($4.6 \times 10^9$)

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17. Why are the four inner planets so rocky?

    Hint

    The inner planets are closest to the sun. How did this affect their formation?

    Solution

    In the early solar system, temperatures in this region were so hot that they vaporized the lighter elements.

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18. What are some of the more common heavy elements that formed our planet?

    Hint

    Which elements were able to survive the heat of the early solar system?

    Solution

    Iron, silicon, magnesium, sulfur, aluminum, calcium and nickel

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