About Space physics in O Level Physics
Space physics is one of the 14 main topics in our O Level Physics (Cambridge (CAIE) 5054) question bank, and about 2% of its real questions come from it. Tayyari Karo has 17 real questions on this topic from 2023 to 2026, from Paper 1, Paper 2; 8 are multiple choice and marked instantly, and the rest are structured questions with a model answer. By difficulty: 11 medium, 4 easy, 2 hard.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
Try 8 real questions
These are real past-paper questions. Think of your answer first, then open the explanation.
May/June 2025 · Paper 1 · Space physics
The orbital speed of a planet around the Sun is v and its orbital period is T. Jupiter is further from the Sun than the Earth.
Which planet has the greater value for v and which planet has the greater value for T?
- greater v: Earth; greater T: Earth
- greater v: Earth; greater T: Jupiter
- greater v: Jupiter; greater T: Jupiter
- greater v: Jupiter; greater T: Earth
Show answer and explanation
Answer: B. greater v: Earth; greater T: Jupiter
The Sun gravitational pull is weaker further out, so Jupiter moves more slowly than the Earth, and it also has a much longer path, so its orbital period is far greater.
May/June 2025 · Paper 1 · Space physics
What is the Earth position in the order of planets from the Sun?
- closest planet to the Sun
- second closest planet to the Sun
- third closest planet to the Sun
- fourth closest planet to the Sun
Show answer and explanation
Answer: C. third closest planet to the Sun
The order outwards from the Sun is Mercury, Venus, Earth, Mars, so the Earth is third.
Oct/Nov 2025 · Paper 1 · Space physics
The planets in the Solar System orbit the Sun.
Which statement is correct?
- There is a force on each planet away from the Sun.
- There is a force on each planet in the direction in which it travels.
- There is a force on each planet opposite to the direction in which it travels.
- There is a force on each planet towards the Sun.
Show answer and explanation
Answer: D. There is a force on each planet towards the Sun.
The Sun's gravitational pull provides the centripetal force that keeps each planet in orbit, and this force always acts towards the centre of the orbit, i.e. towards the Sun.
Oct/Nov 2025 · Paper 1 · Space physics
A star is a distance of 4.2 light-years from the Earth.
What is 4.2 light-years in metres?
- 1.1 × 10¹³ m
- 6.6 × 10¹⁴ m
- 9.5 × 10¹⁵ m
- 4.0 × 10¹⁶ m
Show answer and explanation
Answer: D. 4.0 × 10¹⁶ m
One light-year ≈ 9.46 × 10¹⁵ m, so 4.2 light-years = 4.2 × 9.46×10¹⁵ ≈ 4.0 × 10¹⁶ m.
Oct/Nov 2025 · Paper 1 · Space physics
What is a protostar?
- a cloud of gas that is collapsing and decreasing in temperature
- a cloud of gas that is collapsing and increasing in temperature
- a star that is expanding and decreasing in temperature
- a star that is expanding and increasing in temperature
Show answer and explanation
Answer: B. a cloud of gas that is collapsing and increasing in temperature
A protostar forms as a cloud of gas and dust collapses under gravity; the gravitational compression converts potential energy to heat, so its temperature increases as it collapses.
May/June 2024 · Paper 1 · Space physics
Which statement is correct?
- The orbital speed of the Earth around the Sun is (2π × average diameter of the orbit) ÷ orbital period.
- The orbit of the Earth around the Sun is an ellipse.
- The Moon takes approximately one month to orbit the Sun.
- Light from the Sun takes 5.0 minutes to reach the Earth.
Show answer and explanation
Answer: B. The orbit of the Earth around the Sun is an ellipse.
The Earth's orbit around the Sun is an ellipse; option A has an incorrect factor (circumference = π × diameter, not 2π × diameter), the Moon orbits the Earth (not the Sun) in about a month, and sunlight actually takes about 8.3 minutes to reach Earth.
May/June 2024 · Paper 2 · Space physics
An object has a weight of 37 N on the surface of Mercury (g = 3.7 N/kg). Calculate its weight on the surface of the Earth (g = 9.8 N/kg). Show your working.
Show model answer
weight on Earth = 98 N
mass = weight ÷ g(Mercury) = 37 ÷ 3.7 = 10 kg; weight on Earth = mass × g(Earth) = 10 × 9.8 = 98 N.
May/June 2024 · Paper 2 · Space physics
State what is meant by a 'moon'.
Show model answer
A moon is a natural satellite that orbits a planet.
This is the standard definition distinguishing a moon from an artificial satellite.
