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Practise 31 exam-style questions on Our solar system for AQA GCSE Physics. Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.
Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.
Name the star at the centre of our solar system and state how many planets orbit it.
The Sun. Eight planets orbit it.
Our solar system has only one star, the Sun. Eight planets orbit it: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Pluto is now classed as a dwarf planet, so it is not counted.
the Sun
eight (planets)
allow 8; do not accept nine
Give one similarity and one difference between a planet and a dwarf planet.
Similarity: both planets and dwarf planets orbit the Sun. Difference: dwarf planets are much smaller than planets.
Dwarf planets such as Pluto and Ceres orbit the Sun just like planets, but they are much smaller and share their orbits with many other objects. Moons are different again because they orbit planets.
similarity: both orbit the Sun
allow both are (roughly spherical) natural objects in the solar system; allow both can have moons
difference: dwarf planets are (much) smaller (than planets)
allow dwarf planets have not cleared other objects from their orbits
The Sun is in equilibrium now, but it will not stay in equilibrium forever.
Explain why.
The Sun is fusing hydrogen in its core, and eventually the hydrogen there will run out. Hydrogen fusion in the core will then stop, so the outward force due to fusion energy will no longer balance the inward pull of gravity. The balance is lost and the Sun will change: its core will contract while its outer layers expand, and it will become a red giant.
Equilibrium only lasts while there is fuel for fusion. The Sun has enough hydrogen for about 10 billion years in total, and is roughly halfway through its main sequence stage.
the hydrogen in the core will eventually run out / be used up
so hydrogen fusion in the core stops and the outward force no longer balances gravity
allow energy release changes so the forces are unbalanced
so the star changes size (the core contracts and the outer layers expand into a red giant)
allow the Sun will become a red giant
The mean distance from the Sun to the Earth is 150 million km. Light travels at 3.0 × 10⁸ m/s.
Calculate the time taken for light to travel from the Sun to the Earth.
Give your answer in minutes.
distance = 150 million km = 150 × 10⁶ × 1000 m = 1.5 × 10¹¹ m
distance = speed × time
1.5 × 10¹¹ = 3.0 × 10⁸ × t
t = 1.5 × 10¹¹ ÷ 3.0 × 10⁸ = 500 s
500 ÷ 60 = 8.3 minutes
Convert million kilometres to metres carefully: 1 million km = 10⁶ km = 10⁹ m. Even at the speed of light, sunlight takes over 8 minutes to reach us, which shows how large the solar system is.
150 million km = 1.5 × 10¹¹ m
an answer of 8.3 (minutes) scores 4 marks
1.5 × 10¹¹ = 3.0 × 10⁸ × t
allow t = 1.5 × 10¹¹ ÷ 3.0 × 10⁸; allow ecf from an incorrect conversion
t = 500 (s)
allow ecf
500 ÷ 60 = 8.3 (minutes)
allow 8.33 / 8 min 20 s; allow ecf
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