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Moons of our Solar System
Moons of our Solar System

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1.6 What do you know?

This activity gives you the chance to find out what you already know about moons. It’s a very basic non-scored quiz. Don’t worry if you don’t know some of the answers. Take an educated guess, and whether right or wrong you’ll get some feedback that we hope will help you to understand things a little better.

Activity 1 What do you already know about moons?

Timing: Allow approximately 15 minutes.

The scale of the Solar System. How far is the Moon from the Earth?

a. 

400 thousand km


b. 

150 million km


c. 

4.5 billion km


The correct answer is a.

a. 

Correct. The Moon is on average about 400 thousand km from the Earth. 150 million km is the distance from the Earth to the Sun, whereas 4.5 billion km is the distance from the Sun to Neptune, the most distant planet.


Planets without moons. Which planets in our Solar System have no known moon?

a. 

Only Venus


b. 

Venus and Mercury


c. 

Venus, Mercury and Neptune


The correct answer is b.

b. 

Correct. Neither Venus nor Mercury has a known moon and if one exists it can’t be much more than a kilometre in size. Neptune has at least 13 moons.


Orbits. What shape is a moon’s orbit?

a. 

A circle


b. 

Egg-shaped


c. 

An ellipse


The correct answer is c.

c. 

Correct. Orbits are ellipses. In many cases they are almost circular, but measured carefully the diameter across one direction is slightly longer than the diameter measured in a different direction. (We are describing a moon’s orbit relative to its planet here. In fact, because a planet is travelling round the Sun, its moon’s orbit traces a more complicated path.)