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Grade 9 · Science · Unit 10 of 12

Motion in Our Universe

Orbits, gravity, planets, stars and galaxies

What your child practises

How gravity keeps planets in orbit, rotation and revolution, the seasons, the Moon, the planets, stars, galaxies, and how light-years measure huge distances.

Saskatchewan Curriculum outcome: EU9.1 · the motion and characteristics of astronomical bodies in the solar system and the universe

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    What is a star?

    ⭐
    • a burning rock
    • a planet that reflects light
    • a huge ball of hot gas that gives off its own light
    • a large moon
    Show answer

    a huge ball of hot gas that gives off its own light

    Hint: Stars make light and heat by nuclear fusion in their cores.

  2. Question 2

    What kind of object is the Sun?

    ☀️
    • a comet
    • a star
    • a planet
    • a moon
    Show answer

    a star

    Hint: The Sun is the star at the centre of our solar system.

  3. Question 3

    Put these planets in order from closest to the Sun to farthest from the Sun.

    • ⚫Mercury
    • 🟠Jupiter
    • 🌍Earth
    • 🔴Mars
    • 🔵Neptune
    Show answer

    Mercury → Earth → Mars → Jupiter → Neptune

    Hint: Mercury, Venus, Earth, Mars, then the asteroid belt, then Jupiter, Saturn, Uranus and Neptune.

  4. Question 4

    Is it a rocky planet or a giant planet? Tap a planet, then tap its basket.

    Sort into: 🪨 rocky planet · 🪐 giant planet

    • 🌀Neptune
    • 🟡Venus
    • 🔴Mars
    • 🌍Earth
    • 🔵Uranus
    • 🟠Jupiter
    Show answer

    🪨 rocky planet: Venus, Mars, Earth · 🪐 giant planet: Neptune, Uranus, Jupiter

    Hint: The four inner planets are small and rocky. The four outer planets are much larger and made mostly of gas and ice.

  5. Question 5

    What is the Moon?

    🌙
    • a planet
    • a natural satellite that orbits Earth
    • a star
    • a comet
    Show answer

    a natural satellite that orbits Earth

    Hint: A natural satellite is a body that orbits a planet.

  6. Question 6

    Light from a star is 10 light-years away. What does that tell you about what you see?

    🔭
    • you see the star as it is right now
    • the star is 10 years old
    • you see the star as it was 10 years ago
    • the star will die in 10 years
    Show answer

    you see the star as it was 10 years ago

    Hint: Light takes 10 years to reach us, so we see the past.

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