The Solar System

The Sun, planets, moons and other bodies, and how we explore them.

9 questions, free, marked as you go with a worked explanation on every one.

What this covers

• the solar system

The questions

1. How many planets are there in our solar system?
2. What is at the centre of our solar system?
3. Which of these best describes the four inner planets?
4. Why does it take Neptune much longer than Earth to orbit the Sun once?
5. Which of these orbit the Sun? Select all that apply.
6. Why do we send robotic probes to other planets instead of people?
7. Sunlight takes about 500 seconds to travel from the Sun to Earth. Mars orbits about 1.5 times as far from the Sun as Earth does. About how many seconds does sunlight take to reach Mars?
8. A moving object keeps going in a straight line unless a force acts on it. What keeps each planet curving around the Sun instead of flying off into space?
9. Use the table. Which planet is the second closest to the Sun?

Answer these free