The Solar System Quiz

Grade 7 · Science · Quiz

10-question quiz on the Sun, planets, moons, and other objects in our solar system.

Questions

1. How many planets are in our solar system?

   1. 7
   2. 8
   3. 9
   4. 10
   Show answer

   Answer: 8

   There are 8 official planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto was reclassified as a dwarf planet in 2006.

2. Jupiter is the largest planet in our solar system.

   Show answer

   Answer: True

   Jupiter is by far the largest planet — so large that all other planets could fit inside it with room to spare. It has over 2.5 times the mass of all other planets combined.

3. The planet with the most extreme tilt, rotating nearly on its side, is ___.

   Show answer

   Answer: Uranus

   Uranus has an axial tilt of about 98°, meaning it essentially rolls on its side as it orbits the Sun. This gives it extreme seasons — 42 years of sunlight followed by 42 years of darkness at the poles.

4. Which planet is closest to the Sun?

   1. Venus
   2. Mars
   3. Mercury
   4. Earth
   Show answer

   Answer: Mercury

   Mercury is the innermost planet, orbiting just 57.9 million km from the Sun on average. Despite being closest, it is not the hottest — Venus is (due to its greenhouse effect).

5. Saturn is the only planet in the solar system with rings.

   Show answer

   Answer: False

   All four gas/ice giant planets have ring systems. Jupiter, Uranus, and Neptune have rings, but they are thin and faint compared to Saturn's magnificent visible rings.

6. What is the main reason Pluto was reclassified as a dwarf planet in 2006?

   1. It is too small to orbit the Sun
   2. It has not cleared the neighborhood of its orbit
   3. It does not have a moon
   4. It is not spherical
   Show answer

   Answer: It has not cleared the neighborhood of its orbit

   The IAU's 2006 definition requires a planet to: orbit the Sun, be roughly spherical, AND have cleared the neighborhood of its orbit. Pluto fails the third criterion because it orbits in the debris-filled Kuiper Belt.

7. The four inner rocky planets are called ___ planets.

   Show answer

   Answer: terrestrial

   Terrestrial planets (from the Latin 'terra' = earth) are rocky with solid surfaces. They are smaller and denser than the outer gas/ice giants.

8. The Sun is the largest object in the solar system.

   Show answer

   Answer: True

   The Sun contains 99.86% of all the mass in the solar system. Its diameter is about 109 times Earth's diameter.

9. Which planet is known as the 'Red Planet'?

   1. Jupiter
   2. Venus
   3. Mercury
   4. Mars
   Show answer

   Answer: Mars

   Mars appears red due to iron oxide (rust) on its surface. It also has the largest volcano in the solar system (Olympus Mons) and evidence of ancient liquid water.

10. What causes Earth's ocean tides?

    1. Earth's rotation
    2. The Moon's gravity
    3. Solar wind
    4. The Sun's heat
    Show answer

    Answer: The Moon's gravity

    The Moon's gravitational pull creates tidal bulges in Earth's oceans. As Earth rotates under these bulges, coastal areas experience high and low tides roughly twice a day.

Get a personalized course on The Solar System built around your child.