Planets and the Solar System
Year 6 students describe the features of our solar system including the Sun, planets, moons, and other bodies, and explain how gravity governs orbital motion.
What You Need to Know
Key Concept Diagram
Our solar system contains eight planets that orbit the Sun in elliptical paths, held by the Sun's gravity
The inner rocky planets (Mercury, Venus, Earth, Mars) are smaller and denser than the outer gas giants (Jupiter, Saturn, Uranus, Neptune)
Moons are natural satellites that orbit planets; Earth has one moon, while Jupiter has more than 90
The distance between planets is vast — astronomers use the astronomical unit (AU) where 1 AU equals the Earth–Sun distance
Key Vocabulary
Orbit
The curved path one object takes around another due to gravity
Gravity
The attractive force that pulls objects with mass towards each other
Astronomical unit (AU)
The average distance from Earth to the Sun, approximately 150 million km
Gas giant
A large planet composed mainly of hydrogen and helium, such as Jupiter or Saturn
Knowledge Check
Select the correct answer for each question. Click "Check Answer" to see if you are right.
Question 1
What force keeps the planets in orbit around the Sun?
Question 2
Which group correctly lists the four inner rocky planets?
Question 3
If Earth is 1 AU from the Sun and Mars is approximately 1.5 AU from the Sun, how much farther from the Sun is Mars than Earth?
Key Concepts Summary
- ●Our solar system contains eight planets that orbit the Sun in elliptical paths, held by the Sun's gravity
- ●The inner rocky planets (Mercury, Venus, Earth, Mars) are smaller and denser than the outer gas giants (Jupiter, Saturn, Uranus, Neptune)
- ●Moons are natural satellites that orbit planets; Earth has one moon, while Jupiter has more than 90
- ●The distance between planets is vast — astronomers use the astronomical unit (AU) where 1 AU equals the Earth–Sun distance